Image decoding method and apparatus according to block division structure in image coding system

ABSTRACT

Provided is a video decoding method performed by a decoding apparatus, which includes: obtaining split information for a target block from a bitstream; splitting the target block into a first sub-block and a second sub-block based on a split boundary indicated by the split information; deriving a first motion information candidate list for the first sub-block and a second motion information candidate list for the second sub-block based on the split information for the target block; performing inter prediction of the first sub-block based on the first motion information candidate list; and performing inter prediction of the second sub-block based on the second motion information candidate list, in which the first sub-block and the second sub-block are non-rectangular blocks, and the first motion information candidate list for the first sub-block is different from the second motion information candidate list for the second sub-block.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/971,883, filed on Aug. 21, 2020, which is a National Stageapplication under 35 U.S.C. § 371 of International Application No.PCT/KR2018/002177, filed on Feb. 22, 2018. The disclosures of the priorapplications are incorporated by reference in their entirety.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

The present disclosure relates to video coding technology, and moreparticularly, to a video decoding method and a video decoding apparatusaccording to a block split structure in a video coding system.

Related Art

Demand for high-resolution, high-quality images such High Definition(HD) images and Ultra High Definition (UHD) images have been increasingin various fields. As the image data has high resolution and highquality, the amount of information or bits to be transmitted increasesrelative to the legacy image data. Accordingly, when image data istransmitted using a medium such as a conventional wired/wirelessbroadband line or image data is stored using an existing storage medium,the transmission cost and the storage cost thereof are increased.

Accordingly, there is a need for a highly efficient image compressiontechnique for effectively transmitting, storing, and reproducinginformation of high resolution and high quality images.

SUMMARY OF THE DISCLOSURE

The present disclosure provides a method and an apparatus for increasingvideo coding efficiency.

The present disclosure also provides a method and an apparatus forpredicting a target block split through a geometry partition (GP)structure.

The present disclosure also provides a method and an apparatus forderiving neighboring blocks for deriving motion information candidatesof blocks split through the geometry partition (GP) structure.

The present disclosure also provides a method and an apparatus forperforming filtering of the blocks split through the GP structure.

The present disclosure also provides a method and an apparatus forperforming transforming of the blocks split through the GP structure.

In an aspect, a video decoding method performed by a decoding apparatusis proposed. The method includes: obtaining split information for atarget block from a bitstream; splitting the target block into a firstsub-block and a second sub-block based on a split boundary indicated bythe split information; deriving a first motion information candidatelist for the first sub-block and a second motion information candidatelist for the second sub-block based on the split information for thetarget block; performing inter prediction of the first sub-block basedon the first motion information candidate list; and performing interprediction of the second sub-block based on the second motioninformation candidate list, in which the first sub-block and the secondsub-block are non-rectangular blocks, and the first motion informationcandidate list for the first sub-block is different from the secondmotion information candidate list for the second sub-block.

In another aspect, a decoding apparatus performing video decoding isproposed. The decoding apparatus includes: an entropy decoder obtainingsplit information for a target block from a bitstream; a picturesplitting the target block into a first sub-block and a second sub-blockbased on a split boundary indicated by the split information; and apredictor deriving a first motion information candidate list for thefirst sub-block and a second motion information candidate list for thesecond sub-block based on the split information for the target block,performing inter prediction of the first sub-block based on the firstmotion information candidate list, and performing inter prediction ofthe second sub-block based on the second motion information candidatelist, in which the first sub-block and the second sub-block arenon-rectangular blocks, and the first motion information candidate listfor the first sub-block is different from the second motion informationcandidate list for the second sub-block.

In yet another aspect, a video encoding method performed by an encodingapparatus is proposed. The method includes: splitting a target blockinto a first sub-block and a second sub-block; deriving a first motioninformation candidate list for the first sub-block and a second motioninformation candidate list for the second sub-block based on a splittype of the target block; performing inter prediction of the firstsub-block based on the first motion information candidate list;performing inter prediction of the second sub-block based on the secondmotion information candidate list, and encoding and transmitting splitinformation and residual information for the target block, in which thefirst sub-block and the second sub-block are non-rectangular blocks, andthe first motion information candidate list for the first sub-block isdifferent from the second motion information candidate list for thesecond sub-block.

In still yet another aspect, a video encoding apparatus is proposed. Theencoding apparatus includes: a picture partitioner splitting a targetblock into a first sub-block and a second sub-block; a predictorderiving a first motion information candidate list for the firstsub-block and a second motion information candidate list for the secondsub-block based on a split type of the target block, performing interprediction of the first sub-block based on the first motion informationcandidate list, and performing inter prediction of the second sub-blockbased on the second motion information candidate list; and an entropyencoder encoding and transmitting split information and residualinformation for the target block, in which the first sub-block and thesecond sub-block are non-rectangular blocks, and the first motioninformation candidate list for the first sub-block is different from thesecond motion information candidate list for the second sub-block.

According to the present disclosure, according to split types of blockssplit through a GP structure, spatial motion information candidates ofthe blocks can be derived, thereby enhancing prediction efficiency andenhancing overall coding efficiency.

According to the present disclosure, according to the split types ofblocks split through the GP structure, temporal motion informationcandidates of the blocks can be derived, thereby enhancing theprediction efficiency and enhancing the overall coding efficiency.

According to the present disclosure, filtering samples around a boundaryof the blocks split through the GP structure can be performed, therebyenhancing prediction accuracy and enhancing the overall codingefficiency.

According to the present disclosure, a transform process of the blockssplit through the GP structure can be performed, thereby enhancingtransform efficiency and enhancing the overall coding efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a configuration of a videoencoding apparatus to which the present disclosure is applicable.

FIG. 2 is a schematic diagram illustrating a configuration of a videodecoding apparatus to which the present disclosure is applicable.

FIG. 3 exemplarily illustrates CUs split through a QTGP structure and asyntax of the QTGP structure.

FIG. 4 illustrates an example in which the syntaxes of the QTGPstructure for a target CU are transmitted.

FIG. 5 exemplarily illustrates a split boundary derived based oninformation on a split structure and/or a distance from a center pointof the CU.

FIG. 6 exemplarily illustrates spatial neighboring blocks of a targetblock.

FIGS. 7A to 7C exemplarily illustrate types of blocks split through a GPstructure and locations of neighboring blocks used for motion vectorprediction of the blocks in each type.

FIG. 8 exemplarily illustrates a temporal neighboring block of thetarget block.

FIGS. 9A and 9B exemplarily illustrate types of blocks split through aGP structure and locations of temporal neighboring blocks used formotion vector prediction of the blocks in each type.

FIG. 10 exemplarily illustrates a boundary region between a firstsub-block and a second sub-block split through the GP structure.

FIG. 11 exemplarily illustrates samples for which filtering foroverlapped motion compensation is performed.

FIG. 12 illustrates an example of the first sub-block and the secondsub-block for which one transform process is performed.

FIG. 13 illustrates an example of the first sub-block and the secondsub-block for which a separate transform process is performed.

FIG. 14 schematically illustrates a video encoding method by an encodingapparatus according to the present disclosure.

FIG. 15 schematically illustrates a video decoding method by a decodingapparatus according to the present disclosure.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present disclosure may be modified in various forms, and specificembodiments thereof will be described and illustrated in the drawings.However, the embodiments are not intended for limiting the disclosure.The terms used in the following description are used to merely describespecific embodiments, but are not intended to limit the disclosure. Anexpression of a singular number includes an expression of the pluralnumber, so long as it is clearly read differently. The terms such as“include” and “have” are intended to indicate that features, numbers,steps, operations, elements, components, or combinations thereof used inthe following description exist and it should be thus understood thatthe possibility of existence or addition of one or more differentfeatures, numbers, steps, operations, elements, components, orcombinations thereof is not excluded.

Meanwhile, elements in the drawings described in the disclosure areindependently drawn for the purpose of convenience for explanation ofdifferent specific functions, and do not mean that the elements areembodied by independent hardware or independent software. For example,two or more elements of the elements may be combined to form a singleelement, or one element may be split into plural elements. Theembodiments in which the elements are combined and/or split belong tothe disclosure without departing from the concept of the disclosure.

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the accompanying drawings. Further, likereference numerals are used to indicate like elements throughout thedrawings, and the same descriptions on the like elements will beomitted.

In the present specification, generally a picture means a unitrepresenting an image at a specific time, a slice is a unit constitutinga part of the picture. One picture may be composed of plural slices, andthe terms of a picture and a slice may be mixed with each other asoccasion demands.

A pixel or a pel may mean a minimum unit constituting one picture (orimage). Further, a “sample” may be used as a term corresponding to apixel. The sample may generally represent a pixel or a value of a pixel,may represent only a pixel (a pixel value) of a luma component, and mayrepresent only a pixel (a pixel value) of a chroma component.

A unit indicates a basic unit of image processing. The unit may includeat least one of a specific area and information related to the area.Optionally, the unit may be mixed with terms such as a block, an area,or the like. In a typical case, an M×N block may represent a set ofsamples or transform coefficients arranged in M columns and N rows.

FIG. 1 is a schematic diagram illustrating a configuration of a videoencoding apparatus to which the present disclosure is applicable.

Referring to FIG. 1, a video encoding apparatus (100) may include apicture partitioner (105), a predictor (110), a residual processor(120), an adder (140), a filter (150), and a memory (160). The residualprocessor (120) may include a subtractor (121), a transformer (122), aquantizer (123), a re-arranger (124), a dequantizer (125), an inversetransformer (126).

The picture partitioner (105) may split an input picture into at leastone processing unit.

In an example, the processing unit may be referred to as a coding unit(CU). In this case, the coding unit may be recursively split from thelargest coding unit (LCU) according to a quad-tree binary-tree (QTBT)structure. For example, one coding unit may be split into a plurality ofcoding units of a deeper depth based on a quadtree structure and/or abinary tree structure. In this case, for example, the quad treestructure may be first applied and the binary tree structure may beapplied later. Alternatively, the binary tree structure may be appliedfirst. The coding procedure according to the present disclosure may beperformed based on a final coding unit which is not split any further.In this case, the largest coding unit may be used as the final codingunit based on coding efficiency, or the like, depending on imagecharacteristics, or the coding unit may be recursively split into codingunits of a lower depth as necessary and a coding unit having an optimalsize may be used as the final coding unit. Here, the coding proceduremay include a procedure such as prediction, transform, andreconstruction, which will be described later.

In another example, the processing unit may include a coding unit (CU)prediction unit (PU), or a transform unit (TU). The coding unit may besplit from the largest coding unit (LCU) into coding units of a deeperdepth according to the quad tree structure. In this case, the largestcoding unit may be directly used as the final coding unit based on thecoding efficiency, or the like, depending on the image characteristics,or the coding unit may be recursively split into coding units of adeeper depth as necessary and a coding unit having an optimal size maybe used as a final coding unit. When the smallest coding unit (SCU) isset, the coding unit may not be split into coding units smaller than thesmallest coding unit. Here, the final coding unit refers to a codingunit which is partitioned or split to a prediction unit or a transformunit. The prediction unit is a unit which is partitioned from a codingunit, and may be a unit of sample prediction. Here, the prediction unitmay be split into sub-blocks. The transform unit may be split from thecoding unit according to the quad-tree structure and may be a unit forderiving a transform coefficient and/or a unit for deriving a residualsignal from the transform coefficient. Hereinafter, the coding unit maybe referred to as a coding block (CB), the prediction unit may bereferred to as a prediction block (PB), and the transform unit may bereferred to as a transform block (TB). The prediction block orprediction unit may refer to a specific area in the form of a block in apicture and include an array of predicted samples. Also, the transformblock or transform unit may refer to a specific area in the form of ablock in a picture and include the transform coefficient or an array ofresidual samples.

The predictor (110) may perform prediction on a processing target block(hereinafter, a current block), and may generate a predicted blockincluding predicted samples for the current block. A unit of predictionperformed in the predictor (110) may be a coding block, or may be atransform block, or may be a prediction block.

The predictor (110) may determine whether intra-prediction is applied orinter-prediction is applied to the current block. For example, thepredictor (110) may determine whether the intra-prediction or theinter-prediction is applied in unit of CU.

In case of the intra-prediction, the predictor (110) may derive apredicted sample for the current block based on a reference sampleoutside the current block in a picture to which the current blockbelongs (hereinafter, a current picture). In this case, the predictor(110) may derive the predicted sample based on an average orinterpolation of neighboring reference samples of the current block(case (i)), or may derive the predicted sample based on a referencesample existing in a specific (prediction) direction as to a predictedsample among the neighboring reference samples of the current block(case (ii)). The case (i) may be called a non-directional mode or anon-angular mode, and the case (ii) may be called a directional mode oran angular mode. In the intra-prediction, prediction modes may includeas an example 33 directional modes and at least two non-directionalmodes. The non-directional modes may include DC mode and planar mode.The predictor (110) may determine the prediction mode to be applied tothe current block by using the prediction mode applied to theneighboring block.

In case of the inter-prediction, the predictor (110) may derive thepredicted sample for the current block based on a sample specified by amotion vector on a reference picture. The predictor (110) may derive thepredicted sample for the current block by applying any one of a skipmode, a merge mode, and a motion vector prediction (MVP) mode. In caseof the skip mode and the merge mode, the predictor (110) may use motioninformation of the neighboring block as motion information of thecurrent block. In case of the skip mode, unlike in the merge mode, adifference (residual) between the predicted sample and an originalsample is not transmitted. In case of the MVP mode, a motion vector ofthe neighboring block is used as a motion vector predictor and thus isused as a motion vector predictor of the current block to derive amotion vector of the current block.

In case of the inter-prediction, the neighboring block may include aspatial neighboring block existing in the current picture and a temporalneighboring block existing in the reference picture. The referencepicture including the temporal neighboring block may also be called acollocated picture (colPic). Motion information may include the motionvector and a reference picture index. Information such as predictionmode information and motion information may be (entropy) encoded, andthen output as a form of a bitstream.

When motion information of a temporal neighboring block is used in theskip mode and the merge mode, a highest picture in a reference picturelist may be used as a reference picture. Reference pictures included inthe reference picture list may be aligned based on a picture order count(POC) difference between a current picture and a corresponding referencepicture. A POC corresponds to a display order and may be discriminatedfrom a coding order.

The subtractor (121) generates a residual sample which is a differencebetween an original sample and a predicted sample. If the skip mode isapplied, the residual sample may not be generated as described above.

The transformer (122) transforms residual samples in units of atransform block to generate a transform coefficient. The transformer(122) may perform transform based on the size of a correspondingtransform block and a prediction mode applied to a coding block orprediction block spatially overlapping with the transform block. Forexample, residual samples may be transformed using discrete sinetransform (DST) transform kernel if intra-prediction is applied to thecoding block or the prediction block overlapping with the transformblock and the transform block is a 4×4 residual array and is transformedusing discrete cosine transform (DCT) transform kernel in other cases.

The quantizer (123) may quantize the transform coefficients to generatequantized transform coefficients.

The re-arranger (124) rearranges quantized transform coefficients. There-arranger (124) may rearrange the quantized transform coefficients inthe form of a block into a one-dimensional vector through a coefficientscanning method. Although the re-arranger (124) is described as aseparate component, the re-arranger (124) may be a part of the quantizer(123).

The entropy encoder (130) may perform entropy-encoding on the quantizedtransform coefficients. The entropy encoding may include an encodingmethod, for example, an exponential Golomb, a context-adaptive variablelength coding (CAVLC), a context-adaptive binary arithmetic coding(CABAC), or the like. The entropy encoder (130) may perform encodingtogether or separately on information (e.g., a syntax element value orthe like) required for video reconstruction Further to the quantizedtransform coefficients. The entropy-encoded information may betransmitted or stored in unit of a network abstraction layer (NAL) in abitstream form.

The dequantizer (125) dequantizes values (transform coefficients)quantized by the quantizer (123) and the inverse transformer (126)inversely transforms values dequantized by the dequantizer (125) togenerate a residual sample.

The adder (140) adds a residual sample to a predicted sample toreconstruct a picture. The residual sample may be added to the predictedsample in units of a block to generate a reconstructed block. Althoughthe adder (140) is described as a separate component, the adder (140)may be a part of the predictor (110). Meanwhile, the adder (140) may bereferred to as a reconstructor or reconstructed block generator.

The filter (150) may apply deblocking filtering and/or a sample adaptiveoffset to the reconstructed picture. Artifacts at a block boundary inthe reconstructed picture or distortion in quantization may be correctedthrough deblocking filtering and/or sample adaptive offset. Sampleadaptive offset may be applied in units of a sample after deblockingfiltering is completed. The filter (150) may apply an adaptive loopfilter (ALF) to the reconstructed picture. The ALF may be applied to thereconstructed picture to which deblocking filtering and/or sampleadaptive offset has been applied.

The memory (160) may store a reconstructed picture (decoded picture) orinformation necessary for encoding/decoding. Here, the reconstructedpicture may be the reconstructed picture filtered by the filter (150).The stored reconstructed picture may be used as a reference picture for(inter) prediction of other pictures. For example, the memory (160) maystore (reference) pictures used for inter-prediction. Here, picturesused for inter-prediction may be designated according to a referencepicture set or a reference picture list.

FIG. 2 is a schematic diagram illustrating a configuration of a videodecoding apparatus to which the present disclosure is applicable.

Referring to FIG. 2, a video decoding apparatus (200) may include anentropy decoder (210), a residual processor (220), a predictor (230), anadder (240), a filter (250), and a memory (260). The residual processor(220) may include a re-arranger (221), a dequantizer (222), an inversetransformer (223).

When a bitstream including video information is input, the videodecoding apparatus (200) may reconstruct a video in relation to aprocess by which video information is processed in the video encodingapparatus.

For example, the video decoding apparatus (200) may perform videodecoding using a processing unit applied in the video encodingapparatus. Thus, the processing unit block of video decoding may be, forexample, a coding unit and, in another example, a coding unit, aprediction unit or a transform unit. The coding unit may be split fromthe largest coding unit according to the quad tree structure and/or thebinary tree structure.

A prediction unit and a transform unit may be further used in somecases, and in this case, the prediction block is a block derived orpartitioned from the coding unit and may be a unit of sample prediction.Here, the prediction unit may be split into sub-blocks. The transformunit may be split from the coding unit according to the quad treestructure and may be a unit that derives a transform coefficient or aunit that derives a residual signal from the transform coefficient.

The entropy decoder (210) may parse the bitstream to output informationrequired for video reconstruction or picture reconstruction. Forexample, the entropy decoder (210) may decode information in thebitstream based on a coding method such as exponential Golomb encoding,CAVLC, CABAC, or the like, and may output a value of a syntax elementrequired for video reconstruction and a quantized value of a transformcoefficient regarding a residual.

More specifically, a CABAC entropy decoding method may receive a bincorresponding to each syntax element in a bitstream, determine a contextmodel using decoding target syntax element information and decodinginformation of neighboring and decoding target blocks or information ofsymbol/bin decoded in a previous step, predict bin generationprobability according to the determined context model and performarithmetic decoding of the bin to generate a symbol corresponding toeach syntax element value. Here, the CABAC entropy decoding method mayupdate the context model using information of a symbol/bin decoded for acontext model of the next symbol/bin after determination of the contextmodel.

Information on prediction among information decoded in the entropydecoder (210) may be provided to the predictor (230) and residualvalues, that is, quantized transform coefficients, on which entropydecoding has been performed by the entropy decoder (210) may be input tothe re-arranger (221).

The re-arranger (221) may rearrange the quantized transform coefficientsinto a two-dimensional block form. The re-arranger (221) may performrearrangement corresponding to coefficient scanning performed by theencoding apparatus. Although the re-arranger (221) is described as aseparate component, the re-arranger (221) may be a part of thedequantizer (222).

The dequantizer (222) may de-quantize the quantized transformcoefficients based on a (de)quantization parameter to output a transformcoefficient. In this case, information about deriving a quantizationparameter may be signaled from the encoding apparatus.

The inverse transformer (223) may inverse-transform the transformcoefficients to derive residual samples.

The predictor (230) may perform prediction on a current block, and maygenerate a predicted block including predicted samples for the currentblock. A unit of prediction performed in the predictor (230) may be acoding block or may be a transform block or may be a prediction block.

The predictor (230) may determine whether to apply intra-prediction orinter-prediction based on information on a prediction. In this case, aunit for determining which one will be used between the intra-predictionand the inter-prediction may be different from a unit for generating apredicted sample. Further, a unit for generating the predicted samplemay also be different in the inter-prediction and the intra-prediction.For example, which one will be applied between the inter-prediction andthe intra-prediction may be determined in unit of CU. Further, forexample, in the inter-prediction, the predicted sample may be generatedby determining the prediction mode in unit of PU, and in theintra-prediction, the predicted sample may be generated in unit of TU bydetermining the prediction mode in unit of PU.

In case of the intra-prediction, the predictor (230) may derive apredicted sample for a current block based on a neighboring referencesample in a current picture. The predictor (230) may derive thepredicted sample for the current block by applying a directional mode ora non-directional mode based on the neighboring reference sample of thecurrent block. In this case, a prediction mode to be applied to thecurrent block may be determined by using an intra-prediction mode of aneighboring block.

In the case of inter-prediction, the predictor (230) may derive apredicted sample for a current block based on a sample specified in areference picture according to a motion vector. The predictor (230) mayderive the predicted sample for the current block using one of the skipmode, the merge mode and the MVP mode. Here, motion information requiredfor inter-prediction of the current block provided by the video encodingapparatus, for example, a motion vector and information on a referencepicture index may be obtained or derived based on the information onprediction.

In the skip mode and the merge mode, motion information of a neighboringblock may be used as motion information of the current block. Here, theneighboring block may include a spatial neighboring block and a temporalneighboring block.

The predictor (230) may construct a merge candidate list using motioninformation of available neighboring blocks and use informationindicated by a merge index on the merge candidate list as a motionvector of the current block. The merge index may be signaled by theencoding apparatus. Motion information may include a motion vector and areference picture. When motion information of a temporal neighboringblock is used in the skip mode and the merge mode, a highest picture ina reference picture list may be used as a reference picture.

In the case of the skip mode, a difference (residual) between apredicted sample and an original sample is not transmitted,distinguished from the merge mode.

In the case of the MVP mode, the motion vector of the current block maybe derived using a motion vector of a neighboring block as a motionvector predictor. Here, the neighboring block may include a spatialneighboring block and a temporal neighboring block.

When the merge mode is applied, for example, a merge candidate list maybe generated using a motion vector of a reconstructed spatialneighboring block and/or a motion vector corresponding to a Col blockwhich is a temporal neighboring block. A motion vector of a candidateblock selected from the merge candidate list is used as the motionvector of the current block in the merge mode. The aforementionedinformation on prediction may include a merge index indicating acandidate block having the best motion vector selected from candidateblocks included in the merge candidate list. Here, the predictor (230)may derive the motion vector of the current block using the merge index.

When the MVP (Motion vector Prediction) mode is applied as anotherexample, a motion vector predictor candidate list may be generated usinga motion vector of a reconstructed spatial neighboring block and/or amotion vector corresponding to a Col block which is a temporalneighboring block. That is, the motion vector of the reconstructedspatial neighboring block and/or the motion vector corresponding to theCol block which is the temporal neighboring block may be used as motionvector candidates. The aforementioned information on prediction mayinclude a prediction motion vector index indicating the best motionvector selected from motion vector candidates included in the list.Here, the predictor (230) may select a prediction motion vector of thecurrent block from the motion vector candidates included in the motionvector candidate list using the motion vector index. The predictor ofthe encoding apparatus may obtain a motion vector difference (MVD)between the motion vector of the current block and a motion vectorpredictor, encode the MVD and output the encoded MVD in the form of abitstream. That is, the MVD may be obtained by subtracting the motionvector predictor from the motion vector of the current block. Here, thepredictor (230) may obtain a motion vector included in the informationon prediction and derive the motion vector of the current block byadding the motion vector difference to the motion vector predictor.Further, the predictor may obtain or derive a reference picture indexindicating a reference picture from the aforementioned information onprediction.

The adder (240) may add a residual sample to a predicted sample toreconstruct a current block or a current picture. The adder (240) mayreconstruct the current picture by adding the residual sample to thepredicted sample in units of a block. When the skip mode is applied, aresidual is not transmitted and thus the predicted sample may become areconstructed sample. Although the adder (240) is described as aseparate component, the adder (240) may be a part of the predictor(230). Meanwhile, the adder (240) may be referred to as a reconstructoror reconstructed block generator.

The filter (250) may apply deblocking filtering, sample adaptive offsetand/or ALF to the reconstructed picture. Here, sample adaptive offsetmay be applied in units of a sample after deblocking filtering. The ALFmay be applied after deblocking filtering and/or application of sampleadaptive offset.

The memory (260) may store a reconstructed picture (decoded picture) orinformation necessary for decoding. Here, the reconstructed picture maybe the reconstructed picture filtered by the filter (250). For example,the memory (260) may store pictures used for inter-prediction. Here, thepictures used for inter-prediction may be designated according to areference picture set or a reference picture list. A reconstructedpicture may be used as a reference picture for other pictures. Thememory (260) may output reconstructed pictures in an output order.

When coding for an input picture is performed like the aforementionedcontents, the coding may be performed based on one processing unit. Theprocessing unit may be referred to as a coding unit (CU). Meanwhile, asthe coding is performed in units of regions including similarinformation in the picture, transform efficiency may be enhanced,thereby enhancing overall coding efficiency. Further, as the coding isperformed in units of regions including the similar information in thepicture, prediction accuracy may be enhanced, thereby enhancing theoverall coding efficiency. However, when only a quad tree (QT) structureis applied and the picture is thus split into only square CUs, it may belimited to split the CUs to include only accurately similar information.For example, information indicating a specific object in the picture maybe positioned widely in a diagonal direction and in this case, when theinformation indicating the specific object is included in one CU, a lotof information other than the information indicating the specific objectmay be included and when the information indicating the specific objectis included in a plurality of square CUs, coding for each of theplurality of CUs should be performed, and as a result, the codingefficiency may deteriorate. In this case, the coding efficiency may befurther enhanced by splitting the picture into a non-square CU includingthe information indicating the specific object. Therefore, a method forsplitting an input picture into a square CU and a non-square CU byapplying another split structure together with the quad tree structuremay be proposed. Therefore, the picture may be split into various typesof CUs according to the information in the picture and the coding may bemore efficiently performed. For example, the picture may be splitthrough a quad tree geometry partition (QTGP) structure.

FIG. 3 exemplarily illustrates CUs split through a QTGP structure and asyntax of the QTGP structure.

The QTGP structure may indicate a structure in which a CU (or CTU) issplit through a QT structure and through a geometry partition (GP)structure. The GP structure may also be called a geometry tree (GT)structure. That is, the QTGP structure may indicate a split structureconfigured in a form in which the QT structure and the GP structure arecombined and when the picture is coded in units of CTU, the CTU may besplit through the QT structure and a leaf node of the QT structure maybe additionally split through the GP structure. Here, the GP structuremay indicate a structure in which the CU is split into various types ofnon-square sub-CUs. That is, various types of non-square sub-CUs may bederived in addition to non-square sub-CUs having a size of N×2N or 2N×N.Referring to FIG. 3A, the CU may be split into lower-depth square CUsthrough the QT structure and additionally, a specific CU among thesquare CUs may be split into lower-depth non-square CUs through the GPstructure.

FIG. 3B may illustrate an example in which the syntax of the QTGPstructure is transmitted. A solid line illustrated in FIG. 3B mayindicate the QT structure and a dotted line may indicate the GPstructure. Further, from top to bottom, the syntax for the CU of a lowerdepth at a higher depth may be illustrated. Further, in the directionfrom left to right, the syntaxes for upper-left, upper-right,lower-left, and lower-right CUs may be illustrated. Specifically, anuppermost number may indicate the syntax for a CU of n depth, numbers ata second position from the top may indicate CUs of n+1 depth, numbers ata third position from the top may indicate CUs of n+2 depth, and numbersat a fourth position from the top may indicate syntaxes for CUs of n+3depth. In addition, numbers displayed in bold may indicate values ofsyntaxes for the QT structure and numbers not displayed in bold mayindicate values for syntaxes for the GP structure.

Referring to FIG. 3B, a QT split flag indicating whether the CU is splitthrough the QT structure may be transmitted. That is, a flag indicatingwhether the 2N×2N sized CU is split into four N×N sized sub-CUs may betransmitted. QT_split_flag may indicate a syntax element for the QTsplit flag. For example, when the value of the QT split flag for the CUis 1, the CU may be split into four sub-CUs and when the value of the QTsplit flag for the CU is 0, the CU may not be split. Further, in orderto adjust the QT structure for an input image, information on a maximumCU size, a minimum CU size, a maximum depth, etc., in the QT structuremay be transmitted. The information for the QT structure may betransmitted for each of slice types or transmitted for each of imagecomponents (luminance component, chroma component, etc.).

Referring to FIG. 3B, information on the GP structure may be transmittedto a terminal node that is no longer split in the QT structure. That is,the information on the GP structure for a corresponding to the terminalnode may be transmitted in the QT structure. Here, information includingthe information on the GP structure may be called GP split information.For example, a GP split flag indicating whether the CU is split throughthe GP structure, i.e., whether the GP structure is applied to the CUmay be transmitted. GP_split_flag (or GT_split_flag) may indicate asyntax element for the GP split flag. Specifically, when the value ofthe GP split flag is 1, the CU may be split into two sub-CUs and whenthe value of the GP split flag is 0, the CU may not be split.

Meanwhile, when the GP split flag for the CU indicates that the GPstructure is applied to the CU, information on a split angle and/or adistance from a center of the CU may be transmitted in order to derive asplit type through the GP structure. That is, information on a splitboundary for the CU may be transmitted and the CU may be split based ona split boundary derived based on the information.

FIG. 4 illustrates an example in which the syntaxes of the QTGPstructure for a target CU are transmitted.

Referring to FIG. 4, QT_split_flag for a target CU may be transmitted.The QT_split_flag may indicate whether the target CU is split throughthe QT structure as described above. That is, the QT_split_flag mayindicate whether the target CU is split into sub-CUs having sizes of ahalf height and a half width of the target CU.

Specifically, for example, when the value of the QT_split_flag of thetarget CU is 1, i.e., when the QT_split_flag indicates that the targetCU is split into the sub-CUs having the sizes of the half height and thehalf width of the target CU, the target CU may be split into thesub-CUs. In this case, the QT_split_flag for the sub-CUs may betransmitted. That is, the target CU is split into even lower-depth CUscoding-recursively and CUs of the terminal node which is no longer splitmay be derived.

Meanwhile, when the value of the QT_split_flag of the target CU of theterminal node is 0, i.e., when the QT_split_flag indicates that thetarget CU is not split into the sub-CUs having the sizes of the halfheight and the half width of the target CU, GP_split_flag for the targetCU may be transmitted. The GP_split_flag may indicate whether the targetCU is split through the GP structure as described above. That is, theGP_split_flag may indicate whether the target CU having the 2N×2N sizeis split into various types of non-square sub-CUs, for example. When theGP structure is applied to the target CU, shapes of the CUs split fromthe target CU may be determined according to the GP_split_flag and aGP_mode value.

Specifically, when the value of the GP_split_flag is 1, the target CUmay be split into split types indicated by the GP_mode and when thevalue of the GP_split_flag is 0, the split type of the target CU may bederived as a 2N×2N type. In other words, when the value of theGP_split_flag is 0, the target CU having the 2N×2N size may not besplit. When the GP_split_flag indicates that the target CU is splitthrough the GP structure, the GP_mode for the target CU may betransmitted. The GP_mode may be an index indicating in which directionthe target CU is split, i.e., the split type of the target CU. The indexindicating the split type may be called a GP split mode index. In thiscase, the split type of the CU may be derived based on the index and theCU may be split into non-square sub-CUs based on the split type. Forexample, (N/4)×2N type, (N/2)×2N type, N×2N type, 2N×N type and2N×(N/2), 2N×(N/4) type may be preset to the specific split types andthe index may indicate one of the types.

Further, syntaxes of the QTGP structure may be shown as in the followingtable.

TABLE 1 De- scrip- tor coding quadtree ( x0, y0, log2CbSize, cqtDepth ){ QT _(—) split _(—) flag[ x0 ][ y0 ] ae(v) if( QT split flag[ x0 ][ y0] ) { x1 = x0 + ( 1 << ( log2CbSize − 1 ) ) y1 = y0 + ( 1 << (log2CbSize − 1 ) ) coding quadtree( x0, y0, log2CbSize − 1, cqtDepth + 1) if( x1 < pic width in luma samples ) coding quadtree ( x1, y0,log2CbSize − 1, cqtDepth + 1) if( y1 < pic height in luma samples )coding quadtree ( x0, y1, log2CbSize − 1, cqtDepth + 1 ) if( x1 < picwidth in luma samples && y1 < pic height in luma samples ) codingquadtree ( x1, y1, log2CbSize − 1, cqtDepth + 1 ) } else { GP _(—) split_(—) flag[ x0 ][ y0 ] ae(v) if ( GP_split_flag[ x0 ][ y0 ]) { GP _(—)mode[ x0 ][ y0 ] ae(v) coding_unit ( x0, y0, log2CbSize, log2CbSize, GP0) coding_unit ( x0, y0, log2CbSize, log2CbSize, GP1 ) } else {coding_unit( x0, y0, log2CbSize, log2CbSize ) } } }

Here, QT_split_flag may indicate the syntax element of theaforementioned QT_split_flag, GP_split_flag may indicate the syntaxelement of the aforementioned GP_split_flag, and GP_mode may indicatethe syntax element of the aforementioned GP split mode index.

Meanwhile, when the GP split flag for the CU indicates that the GPstructure is applied to the CU, the information on the split angleand/or the distance from the center of the CU may be transmitted inorder to derive the split type through the GP structure. That is, theinformation on the split boundary for the CU may be transmitted and theCU may be split based on the split boundary derived based on theinformation.

FIG. 5 exemplarily illustrates a split boundary derived based oninformation on a split structure and/or a distance from a center pointof the CU. Referring to FIG. 5, an angle of a direction (or a boundary)in which the CU is split may be derived based on the information on thesplit angle and a location of the boundary at which the CU is split maybe derived based on the information on the distance from the center. Thesplit boundary may be derived based on the information on the splitangle and the information on the distance from the center, and the CUmay be split based on the derived split boundary.

For example, when the value of the split angle derived based on theinformation on the split angle is 0 degree and the distance from thecenter derived from the information on the distance from the center is0, the split boundary may vertically pass through the center of the CUand the CU having the 2N×2N size may be split similarly to a type inwhich is split into N×2N sized sub-CUs in the BT structure. Further,when the value of the split angle derived based on the information onthe split angle is 90 degrees and the distance from the center derivedfrom the information on the distance from the center is 0, the splitboundary may horizontally pass through the center of the CU and the CUhaving the 2N×2N size may be split similarly to a type in which is splitinto N×2N sized sub-CUs in the BT structure. Further, as the split anglefor the CU, 11.25 degrees, 25 degrees, 45 degrees, or 90 degrees may beselectively used according to a split degree and evenly split in anangle range of 360 degrees or unevenly split around a specific angle.

Further, as a unit of the distance from the center, 1 sample, 2 samples,or 4 samples may be selectively used according to the split degree or adistance unit adaptively derived according to the size of the CU may beused. For example, when the size of the CU is a 4×4 size, the unit ofthe distance from the center for the CU may be derived as 1 sample andwhen the size of the CU is an 8×8 size, the unit of the distance fromthe center for the CU may be derived as 2 samples. Therefore, thedistance from the center for the CU may be derived, and as a result, forexample, when a value of split information indicating the distance fromthe center obtained through a bitstream is x, the distance from thecenter may be derived as x samples if the unit of the distance is 1sample and the distance from the center may be derived as 2× samples ifthe unit of the distance is 2 samples. Further, when the size of the CUis a 16×16 size, the unit of the distance from the center may be derivedas 4 samples. Meanwhile, as the distance from the center of the CUincreases, the unit may be applied larger. Specifically, for example,when the size of the CU is a 32×32 size, if the value of the distancefrom the center of the CU is 4 or less, the 1 sample-unit distance maybe used, if the value of the distance from the center is more than 4 and8 or less, the 2 sample-unit distance may be used, and if the value ofthe distance from the center is more than 8, the 4 sample-unit distancemay be used.

In order to indicate the split information for the CU, the syntaxelement for each of the information indicating the split angle and theinformation indicating the distance from the center may be transmittedto a decoding apparatus or one index for the information indicating thesplit information and the distance from the center may be transmitted.

Meanwhile, when inter prediction is applied to a target block split inthe GP structure, motion information of the target block may be derivedbased on motion information of a neighboring block of the target block.Specifically, a motion information candidate list may be configured,which includes candidates representing motion information of neighboringblocks of the target block, an index indicating one of the candidates ofthe motion information candidate list may be received, and the motioninformation of the target block may be derived based on the motioninformation of the candidate indicated by the index. The motioninformation candidate list may indicate a merge candidate list or amotion vector predictor candidate list according to whether a predictionmode of the target block is a merge mode or an MVP mode.

For example, when the merge mode is applied to the target block, a mergecandidate list may be configured, which includes candidates representingthe motion information of the neighboring blocks and motion informationof a candidate which a merge index indicates on the merge candidate listmay be used as the motion information of the target block. The mergeindex may be signaled from an encoding apparatus, and as a result, themerge index may indicate a candidate having optimal motion informationselected among the candidates included in the merge candidate list. Themotion information of the candidate may include a motion vector and areference picture index. The neighboring blocks may include a spatialneighboring block and a temporal neighboring block of the target blockand the merge candidate list may include a spatial candidaterepresenting motion information of the spatial neighboring block and atemporal candidate representing motion information of the temporalneighboring block.

Further, as another example, in the case of a motion vector prediction(MVP) mode, the motion vector predictor candidate list may be generatedin the target block by using a motion vector of a reconstructed spatialneighboring block and/or a motion vector corresponding to a Col blockwhich is the temporal neighboring block. In other words, the motionvector predictor candidate list including the motion vector of thereconstructed spatial neighboring block and/or the motion vectorcorresponding to the temporal neighboring block may be generated as thecandidate. The candidate representing the motion vector of the spatialneighboring block may be represented as a spatial candidate and thecandidate representing the motion vector of the temporal neighboringblock may be represented as a temporal candidate. A motion vectorpredictor flag may be transmitted, which indicates the candidateselected among the candidates included in the motion vector predictorcandidate list and the candidate indicated by the motion vectorpredictor flag among the candidates of the motion vector candidate listmay be selected as the motion vector predictor (MVP) of the targetblock. In this case, a motion vector difference (MVD) between the motionvector of the target block and the MVP may be transmitted through thebitstream and the motion vector of the target block may be derivedthrough addition of the MVD and the MVP.

When the merge candidate list or the MVP candidate list of the targetblock is generated based on the motion information of the neighboringblocks of the target block as described above, the spatial candidatesincluded in the merge candidate list or the MVP candidate list may bederived based on the following spatial neighboring blocks.

FIG. 6 exemplarily illustrates spatial neighboring blocks of a targetblock. In a legacy video coding system, the merge candidate list or MVPcandidate list may be configured based on neighboring blocks at apredetermined location around the target block. For example, asillustrated in FIG. 6, two blocks A0 610 and A1 620 positioned at a leftside of the target block and three blocks B0 630, B1 640, and B2 650 atan upper side of a current block may be selected as the spatialcandidates. Here, A0 610 may be called a lower left neighboring blockand A1 620 may be called a left neighboring block. In addition, B0 630may be called an upper right neighboring block, B1 640 may be called anupper neighboring block, and B2 650 may be called an upper leftneighboring block.

Specifically, when the merge mode is applied to the target block, themerge candidate list may be configured, which includes motioninformation of the A0 610, the A1 620, the B0 630, the B1 640, and/orthe B2 650 as the spatial candidates. Further, when the AMVP mode isapplied to the target block, one motion vector of the A0 610 and the A1620 may be included in the MVP candidate list as the spatial candidateand one motion vector of the B0 630, the B1 640, and the B2 650 may beincluded in the MVP candidate list as the spatial candidate. It may bedetermined whether the motion vector of the neighboring block is used inthe MVP candidate list in the order of the direction illustrated in FIG.6, and as a result, the determination may be performed in the order ofthe A0 610 and the A1 620 and the determination may be performed in theorder of the B0 630, the B1 640, and the B2 650.

Meanwhile, when the target block is a block split through theaforementioned GP structure, the form of the block may be variouslyderived, and as a result, a method for deriving motion information ofthe target block based on a neighboring block at a fixed location maynot be effective. Specifically, there is a high probability that motioninformation of a block adjacent to the target block will be similar tothe motion information of the target block, and the form of the targetblock split through the GP structure may be derived in various forms,and as a result, a location of a most adjacent neighboring block mayvary depending on the form of the target block. Accordingly, changingthe location of the neighboring block used as the candidate for themotion information of the target block based on the form of the targetblock split through the GP structure may be effective to more accuratelyderive the motion information of the target block.

Accordingly, the present disclosure proposes a method for predicting aspatial motion vector according to the form of the target block splitthrough the GP structure. That is, the present disclosure proposeslocations of spatial neighboring blocks according to the form of thetarget block split through the GP structure.

FIGS. 7A to 7C exemplarily illustrate types of blocks split through a GPstructure and locations of neighboring blocks used for motion vectorprediction of the blocks in each type. Referring to FIGS. 7A to 7C, thetarget block may be split into a first sub-block and a second sub-blockthrough the GP structure. Here, the first sub-block may represent ablock positioned at a left side among the blocks split from the targetblock and the second sub-block may represent a block positioned at aright side among the blocks split from the target block. Further, typesof the GP structure may be classified into six first to sixth types.

For example, FIG. 7A(a) may illustrate the first type. As illustrated inFIG. 7A(a), the first type may represent a type in which the firstsub-block has a triangular shape and is split to include a top-leftsample of the target block. When the target block is split into thefirst type, the first sub-block may not be adjacent to a lower leftneighboring block and a left neighboring block of an existing location.Accordingly, motion information of neighboring blocks A0′ and/or A1′ ata location adjacent to the first sub-block instead of the bottom-leftneighboring block and the left neighboring block of the existinglocation may be used as a motion information candidate for predictingthe first sub-block. As illustrated in FIG. 7A(a), the neighboringblocks A0′ and/or A1′ may be positioned approximately at the middle of aleft boundary of the target block. For example, when a left height ofthe first sub-block is LH, and any x component of a top-left sampleposition of the first sub-block is 0 and a y component is 0, thelocation of the neighboring block A0′ of the first sub-block may bederived as (−1, LH), and the location of the neighboring block A1′ ofthe first sub-block may be derived as (−1, LH−1). Alternatively, whenthe left height of the first sub-block is LH, and the x component of thetop-left sample position of the target block is 0 and the y component is0, the location of the neighboring block A0′ of the first sub-block maybe derived as (−1, LH) and the location of the neighboring block A1′ ofthe first sub-block may be derived as (−1, LH−1).

Further, when the target block is split into the first type, the firstsub-block may not be adjacent to the top-left neighboring block and anupper neighboring block of the existing location. Accordingly, motioninformation of neighboring block B0′ and/or B1′ at a location adjacentto the first sub-block instead of the top-right neighboring block andthe upper neighboring block of the existing location may be used as themotion information candidate for predicting the first sub-block. Asillustrated in FIG. 7A(a), the neighboring blocks B0′ and/or B1′ may bepositioned approximately at the middle of an upper boundary of thetarget block. For example, when an upper width of the first sub-block isUW, and the x component of the top-left sample position of the firstsub-block is 0 and the y component is 0, the location of the neighboringblock B0′ of the first sub-block may be derived as (UW, −1) and thelocation of the neighboring block B1′ of the first sub-block may bederived as (UW−1, −1). Alternatively, when the upper width of the firstsub-block is UW, and the x component of the top-left sample position ofthe target block is 0 and the y component is 0, the location of theneighboring block B0′ of the first sub-block may be derived as (UW, −1)and the location of the neighboring block B1′ of the first sub-block maybe derived as (UW−1, −1).

Further, when the target block is split into the first type, the secondsub-block may not be adjacent to the top-left neighboring block of theexisting location. Accordingly, motion information of neighboring blockB2′ at a location adjacent to the second sub-block instead of thetop-left neighboring block of the existing location may be used as amotion information candidate for predicting the second sub-block. Asillustrated in FIG. 7A(a), the neighboring block B2′ may be positionedapproximately at the middle of the upper boundary of the target block.For example, when the upper width of the second sub-block is UW, and thex component of the top-left sample position of the second sub-block is 0and the y component is 0, the location of the neighboring block B2′ ofthe second sub-block may be derived as (−1, −1). Alternatively, when theupper width of the second sub-block is UW, the size of the target blockis N×N, and the x component of the top-left sample position of thetarget block is 0 and the y component is 0, the location of theneighboring block B2′ of the second sub-block may be derived as (N−UW−1,−1).

Further, motion information candidates for the first sub-blocks and thesecond sub-blocks of types 2 to 6 may be derived similarly to the motioninformation candidates of the first sub-blocks and the second sub-blocksof type 1 described above.

For example, FIG. 7A(b) may illustrate the second type. As illustratedin FIG. 7A(b), the second type may represent a type in which the secondsub-block has the triangular shape and is split to include abottom-right sample of the target block. When the target block is splitinto the second type, the second sub-block may not be adjacent to thebottom-left neighboring block and the left neighboring block of theexisting location. Accordingly, motion information of neighboring blockA0′ and/or A1′ at a location adjacent to the second sub-block instead ofthe bottom-left neighboring block and the left neighboring block of theexisting location may be used as the motion information candidate forpredicting the second sub-block. As illustrated in FIG. 7A(b), theneighboring block A0′ and/or A1′ may be positioned approximately at themiddle of a lower boundary of the target block. For example, when alower width of the second sub-block is DW and a right height of thesecond sub-block is RH, and the x component of the top-left sampleposition of the second sub-block is 0 and the y component is 0, thelocation of the neighboring block A0′ of the second sub-block may bederived as (−DW, RH) and the location of the neighboring block A1′ ofthe second sub-block may be derived as (−DW, RH−1). Alternatively, whenthe lower width of the second sub-block is DW and the size of the targetblock is N×N, and the x component of the top-left sample position of thetarget block is 0 and the y component is 0, the location of theneighboring block A0′ of the second sub-block may be derived as (N−1−DW,N) and the location of the neighboring block A1′ of the first sub-blockmay be derived as (N−1−DW, N−1).

Further, when the target block is split into the second type, the secondsub-block may not be adjacent to the top-right neighboring block and theupper neighboring block of the existing location. Accordingly, motioninformation of neighboring B0′ and/or B1′ at a location adjacent to thesecond sub-block instead of the top-right neighboring block and theupper neighboring block of the existing location may be used as themotion information candidate for predicting the second sub-block. Asillustrated in FIG. 7A(b), the neighboring block B0′ and/or B1′ may bepositioned approximately at the middle of a right boundary of the targetblock. For example, when the x component of the top-left sample positionof the second sub-block is 0 and the y component is 0, the location ofthe neighboring block B0′ of the second sub-block may be derived as (1,−1) and the location of the neighboring block B1′ of the secondsub-block may be derived as (0, −1). Alternatively, when the rightheight of the second sub-block is RH and the size of the target block isN×N, and the x component of the top-left sample position of the targetblock is 0 and the y component is 0, the location of the neighboringblock B0′ of the second sub-block may be derived as (N, N−1−RH) and thelocation of the neighboring block B1′ of the second sub-block may bederived as (N−1, N−1−RH).

As another example, FIG. 7B(c) may illustrate the third type. Asillustrated in FIG. 7B(c), the third type may represent a type in whichthe second sub-block has the triangular shape and is split to includethe top-right sample of the target block. When the target block is splitinto the third type, the first sub-block may not be adjacent to thetop-right neighboring block and the upper neighboring block of theexisting location. Accordingly, motion information of neighboring B0′and/or B1′ at a location adjacent to the first sub-block instead of thetop-right neighboring block and the upper neighboring block of theexisting location may be used as the motion information candidate forpredicting the first sub-block. As illustrated in FIG. 7B(c), theneighboring block B0′ and/or B1′ may be positioned approximately at themiddle of the upper boundary of the target block. For example, when theupper width of the first sub-block is UW, and the x component of thetop-left sample position of the first sub-block is 0 and the y componentis 0, the location of the neighboring block B0′ of the first sub-blockmay be derived as (UW, −1) and the location of the neighboring block B1′of the first sub-block may be derived as (UW−1, −1). Alternatively, whenthe upper width of the first sub-block is UW, and the x component of thetop-left sample position of the target block is 0 and the y component is0, the location of the neighboring block B0′ of the first sub-block maybe derived as (UW, −1) and the location of the neighboring block B1′ ofthe first sub-block may be derived as (UW−1, −1).

Further, when the target block is split into the third type, the secondsub-block may not be adjacent to the top-left neighboring block of theexisting location. Accordingly, motion information of neighboring blockB2′ at a location adjacent to the second sub-block instead of thetop-left neighboring block of the existing location may be used as amotion information candidate for predicting the second sub-block. Asillustrated in FIG. 7B(c), the neighboring block B2′ may be positionedapproximately at the middle of the upper boundary of the target block.For example, when the x component of the top-left sample position of thesecond sub-block is 0 and the y component is 0, the location of theneighboring block B2′ of the second sub-block may be derived as (−1,−1). Alternatively, when the upper width of the second sub-block is UWand the size of the target block is N×N, and the x component of thetop-left sample position of the target block is 0 and the y component is0, the location of the neighboring block B2′ of the second sub-block maybe derived as (N−1−UW, −1).

As another example, FIG. 7B(d) may illustrate a fourth type. Asillustrated in FIG. 7B(d), the fourth type may represent a type in whichthe first sub-block has the triangular shape and is split to include thebottom-left sample of the target block. When the target block is splitinto the fourth type, the second sub-block may not be adjacent to thebottom-left neighboring block and the left neighboring block of theexisting location. Accordingly, motion information of neighboring blockA0′ and/or A1′ at a location adjacent to the second sub-block instead ofthe bottom-left neighboring block and the left neighboring block of theexisting location may be used as the motion information candidate forpredicting the second sub-block. As illustrated in FIG. 7B(d), theneighboring block A0′ and/or A1′ may be positioned approximately at themiddle of the lower boundary of the target block. For example, when theupper width of the second sub-block is UW, the lower width of the secondsub-block is DW, and the right height of the second sub-block is RH, andthe x component of the top-left sample position of the second sub-blockis 0 and the y component is 0, the location of the neighboring block A0′of the second sub-block may be derived as (UW−1−DW, RH) and the locationof the neighboring block A1′ of the second sub-block may be derived as(UW−1−DW, RH−1). Alternatively, when the lower width of the secondsub-block is DW and the size of the target block is N×N, and the xcomponent of the top-left sample position of the target block is 0 andthe y component is 0, the location of the neighboring block A0′ of thesecond sub-block may be derived as (N−1−DW, N) and the location of theneighboring block A1′ of the second sub-block may be derived as (N−1−DW,N−1).

As another example, FIG. 7C(e) may illustrate a fifth type. Asillustrated in FIG. 7C(e), the fifth type may represent a type in whichthe first sub-block and the second sub-block have a rectangular shapeand the left boundary of the first sub-block and the right height of thesecond sub-block are split to be the same as the height of the targetblock. Alternatively, the fifth type may represent a type in which thesplit boundary of the target block is split to be in contact with theupper boundary and the lower boundary of the target block.

When the target block is split into the fifth type, the first sub-blockmay not be adjacent to the top-right neighboring block and the upperneighboring block of the existing location. Accordingly, motioninformation of neighboring B0′ and/or B1′ at a location adjacent to thefirst sub-block instead of the top-right neighboring block and the upperneighboring block of the existing location may be used as the motioninformation candidate for predicting the first sub-block. As illustratedin FIG. 7C(e), the neighboring block B0′ and/or B1′ may be positionedapproximately at the middle of the upper boundary of the target block.For example, when the upper width of the first sub-block is UW, and thex component of the top-left sample position of the first sub-block is 0and the y component is 0, the location of the neighboring block B0′ ofthe first sub-block may be derived as (UW, −1) and the location of theneighboring block B1′ of the first sub-block may be derived as (UW−1,−1). Alternatively, when the upper width of the first sub-block is UW,and the x component of the top-left sample position of the target blockis 0 and the y component is 0, the location of the neighboring block B0′of the first sub-block may be derived as (UW, −1) and the location ofthe neighboring block B1′ of the first sub-block may be derived as(UW−1, −1).

Further, when the target block is split into the fifth type, the secondsub-block may not be adjacent to the bottom-left neighboring block andthe left neighboring block of the existing location. Accordingly, motioninformation of neighboring block A0′ and/or A1′ at a location adjacentto the second sub-block instead of the bottom-left neighboring block andthe left neighboring block of the existing location may be used as themotion information candidate for predicting the second sub-block. Asillustrated in FIG. 7C(e), the neighboring block A0′ and/or A1′ may bepositioned approximately at the middle of the lower boundary of thetarget block. For example, when the upper width of the second sub-blockis UW, the lower width of the second sub-block is DW, and the rightheight of the second sub-block is RH, and the x component of thetop-left sample position of the second sub-block is 0 and the ycomponent is 0, the location of the neighboring block A0′ of the secondsub-block may be derived as (UW−1−DW, RH) and the location of theneighboring block A1′ of the second sub-block may be derived as(UW−1−DW, RH−1). Alternatively, when the lower width of the secondsub-block is DW and the size of the target block is N×N, and the xcomponent of the top-left sample position of the target block is 0 andthe y component is 0, the location of the neighboring block A0′ of thesecond sub-block may be derived as (N−1−DW, N) and the location of theneighboring block A1′ of the second sub-block may be derived as (N−1−DW,N−1).

Further, when the target block is split into the fifth type, the secondsub-block may not be adjacent to the top-left neighboring block of theexisting location. Accordingly, motion information of neighboring blockB2′ at a location adjacent to the second sub-block instead of thetop-left neighboring block of the existing location may be used as amotion information candidate for predicting the second sub-block. Asillustrated in FIG. 7C(e), the neighboring block B2′ may be positionedapproximately at the middle of the upper boundary of the target block.For example, when the x component of the top-left sample position of thesecond sub-block is 0 and the y component is 0, the location of theneighboring block B2′ of the second sub-block may be derived as (−1,−1). Alternatively, when the upper width of the second sub-block is UWand the size of the target block is N×N, and the x component of thetop-left sample position of the target block is 0 and the y component is0, the location of the neighboring block B2′ of the second sub-block maybe derived as (N−1−UW, −1).

As another example, FIG. 7C(f) may illustrate a sixth type. Asillustrated in FIG. 7C(f), the sixth type may represent a type in whichthe first sub-block and the second sub-block have a rectangular shapeand the upper boundary of the first sub-block and the lower width of thesecond sub-block are split to be the same as the width of the targetblock. Alternatively, the sixth type may represent a type in which thesplit boundary of the target block is split to be in contact with theleft boundary and the right boundary of the target block.

When the target block is split into the sixth type, the first sub-blockmay not be adjacent to the bottom-left neighboring block and the leftneighboring block of the existing location. Accordingly, motioninformation of neighboring A0′ and/or A1′ at a location adjacent to thefirst sub-block instead of the bottom-left neighboring block and theleft neighboring block of the existing location may be used as a motioninformation candidate for predicting the first sub-block. As illustratedin FIG. 7C(f), the neighboring block A0′ and/or A1′ may be positionedapproximately at the middle of the left boundary of the target block.For example, when a left height of the first sub-block is LH and an xcomponent of a top-left sample position of the first sub-block 0 and a ycomponent is 0, the location of the neighboring block A0′ of the firstsub-block may be derived as (−1, LH) and the location of the neighboringblock A1′ of the first sub-block may be derived as (−1, LH−1).Alternatively, when the left height of the first sub-block is LH and thex component of the top-left sample position of the target block is 0 andthe y component is 0, the location of the neighboring block A0′ of thefirst sub-block may be derived as (−1, LH) and the location of theneighboring block A1′ of the first sub-block may be derived as (−1,LH−1).

Further, when the target block is split into the sixth type, the secondsub-block may not be adjacent to the top-right neighboring block and theupper neighboring block of the existing location. Accordingly, motioninformation of neighboring B0′ and/or B1′ at a location adjacent to thesecond sub-block instead of the top-right neighboring block and theupper neighboring block of the existing location may be used as themotion information candidate for predicting the second sub-block. Asillustrated in FIG. 7C(f), the neighboring block B0′ and/or B1′ may bepositioned approximately at the middle of the left boundary of thetarget block. For example, when the lower width of the second sub-blockis DW, the left height of the second sub-block is LH, and the rightheight of the second sub-block is RH, and the x component of thetop-left sample position of the second sub-block is 0 and the ycomponent is 0, the location of the neighboring block B0′ of the secondsub-block may be derived as (DW, LH−1−RH) and the location of theneighboring block B1′ of the second sub-block may be derived as (DW−1,LH−1−RH). Alternatively, when the right height of the second sub-blockis RH and the size of the target block is N×N, and the x component ofthe top-left sample position of the target block is 0 and the ycomponent is 0, the location of the neighboring block B0′ of the secondsub-block may be derived as (N, N−1−RH) and the location of theneighboring block B1′ of the second sub-block may be derived as (N−1,N−1−RH).

Meanwhile, the first sub-block or the second sub-block is adjacent tothe neighboring block of the existing location to use the motioninformation of the neighboring block as the candidate or when there isno neighboring block adjacent to the first sub-block or the secondsub-block which is replaceable, the motion information of theneighboring block of the existing location may be used as the motioninformation candidate of the first sub-block or the second sub-block.

Meanwhile, when the merge candidate list or the MVP candidate list ofthe target block is generated based on the motion information of theneighboring blocks of the target block as described above, the temporalmotion information candidates included in the merge candidate list orthe MVP candidate list may be derived based on the following temporalneighboring blocks.

FIG. 8 exemplarily illustrates a temporal neighboring block of thetarget block. In a legacy video coding system, the merge candidate listor MVP candidate list may be configured based on a corresponding blockincluded in a reference picture which is a picture different from atarget picture including the target block. Here, the corresponding blockas a block corresponding to the target block may represent a block at alocation corresponding to the target block in the reference picture.

For example, as illustrated in FIG. 8A, a block 810 at a location of alower right neighboring block of the target block in the referencepicture may be derived as the temporal neighboring block. Motioninformation of the temporal neighboring block may be derived as acandidate of the merge candidate list or the MVP candidate list. Whenthe size of the target block is N×N, and the x component of the top-leftsample position of the target block is 0 and the y component is 0, thelocation of the temporal neighboring block in the reference picture maybe derived as (N, N). Here, the reference picture including the temporalneighboring block may also be represented as a co-located picture.

Alternatively, as illustrated in FIG. 8B, a block 820 at a location of acenter lower right neighboring block of the target block in thereference picture may be derived as the temporal neighboring block. Themotion information of the temporal neighboring block may be derived asthe candidate of the merge candidate list or the MVP candidate list.When the size of the target block is N×N, and the x component of thetop-left sample position of the target block is 0 and the y component is0, the location of the temporal neighboring block in the referencepicture may be derived as (N/2, N/2).

Meanwhile, when the target block is a block split through theaforementioned GP structure, the form of the block may be variouslyderived, and as a result, a method for deriving motion information ofthe target block based on a temporal neighboring block at a fixedlocation may not be effective. Accordingly, a method for deriving theblock at the different location as the temporal neighboring blockaccording the form of the target block split through the GP structuremay be effective to more accurately derive the motion information of thetarget block.

Accordingly, the present disclosure proposes a method for predicting atemporal motion vector according to the form of the target block splitthrough the GP structure. That is, the present disclosure proposeslocations of temporal neighboring blocks according to the form of thetarget block split through the GP structure.

FIGS. 9A and 9B exemplarily illustrate types of blocks split through aGP structure and locations of temporal neighboring blocks in thereference picture used for motion vector prediction of the blocks ineach type. Here, the reference picture including the temporalneighboring block may also be represented as a co-located picture.

Referring to FIGS. 9A and 9B, the target block may be split into a firstsub-block and a second sub-block through the GP structure. Here, thefirst sub-block may represent a block positioned at a left side amongthe blocks split from the target block and the second sub-block mayrepresent a block positioned at a right side among the blocks split fromthe target block. Further, types of the GP structure may be classifiedinto six first to sixth types.

For example, FIG. 9A(a) may illustrate the first sub-block and thesecond sub-block of the first type. The first type may represent a typein which the first sub-block has the triangular shape and is split toinclude the top-left sample of the target block. Further, the first typemay represent a type in which the split boundary crosses the upperboundary and the lower boundary of the target block. When the targetblock is split into the first type, the first sub-block may not beadjacent to a location of the top-right neighboring block of the targetblock. Accordingly, motion information of a corresponding blockcorresponding to the bottom-right neighboring block of the target blockin the reference picture may not be similar to the motion information ofthe target block.

The motion information of the corresponding block corresponding to thebottom-right neighboring block of the first sub-block in the referencepicture instead of the corresponding block corresponding to thebottom-right neighboring block of the target block in the referencepicture may be used as the motion information candidate for predictingthe first sub-block. That is, the block at the location of thebottom-right neighboring block of the first sub-block in the referencepicture may be derived as the temporal neighboring block of the firstsub-block and the motion information of the temporal neighboring blockmay be included as the temporal motion information candidate of themerge candidate list or the MVP candidate list. For example, when theleft height of the first sub-block is LH, and the x component of thetop-left sample position of the first sub-block is 0 and the y componentis 0, the location of the temporal neighboring block of the firstsub-block in the reference picture may be derived as (0, LH−1). Thereference picture may also be represented as the co-located picture.Alternatively, when the left height of the first sub-block is LH, andthe x component of the top-left sample position of the target block is 0and the y component is 0, the location of the temporal neighboring blockof the first sub-block in the reference picture may be derived as (0,LH−1).

Meanwhile, when the target block is split into the first type, thesecond sub-block is adjacent to the bottom-right neighboring block ofthe target block in the reference picture unlike the first sub-block,and as a result, the motion information of the bottom-right neighboringblock of the target block in the reference picture may be used as themotion information candidate for predicting the second sub-block. Thatis, the block at the location of the bottom-right neighboring block ofthe corresponding block in the reference picture may be derived as thetemporal neighboring block of the second sub-block and the motioninformation of the temporal neighboring block may be included as thetemporal motion information candidate of the merge candidate list or theMVP candidate list. For example, when the upper width of the secondsub-block is UW and the right height of the second sub-block is RH, andthe x component of the top-left sample position of the second sub-blockis 0 and the y component is 0, the location of the temporal neighboringblock of the second sub-block in the reference picture may be derived as(UW, RH). Alternatively, when the lower width of the second sub-block isDW and the right height of the second sub-block is RH, and the xcomponent of the top-left sample position of the target block is 0 andthe y component is 0, the location of the temporal neighboring block ofthe second sub-block in the reference picture may be derived as (DW,RH). Alternatively, when the size of the target block is N×N, and the xcomponent of the top-left sample position of the target block is 0 andthe y component is 0, the location of the temporal neighboring block ofthe second sub-block in the reference picture may be derived as (N, N).

Further, temporal motion information candidates for the first sub-blocksand the second sub-blocks of types 2 to 6 may be derived similarly tothe motion information candidates of the first sub-block and the secondsub-block of type 1 described above.

For example, FIG. 9A(b) may illustrate the first sub-block and thesecond sub-block of the second type. The second type may represent atype in which the second sub-block has the triangular shape and is splitto include the bottom-right sample of the target block. Further, thesecond type may represent a type in which the split boundary crosses theright boundary and the lower boundary of the target block. When thetarget block is split into the second type, the motion information ofthe corresponding block corresponding to the bottom-right neighboringblock of the first sub-block in the reference picture instead of thecorresponding block corresponding to the bottom-right neighboring blockof the target block in the reference picture may be used as the motioninformation candidate for predicting the first sub-block. That is, theblock at the location of the bottom-right neighboring block of the firstsub-block in the reference picture may be derived as the temporalneighboring block of the first sub-block and the motion information ofthe temporal neighboring block may be included as the temporal motioninformation candidate of the merge candidate list or the MVP candidatelist. For example, when the left height of the first sub-block is LH andthe lower width of the first sub-block is DW, and the x component of thetop-left sample position of the first sub-block is 0 and the y componentis 0, the location of the temporal neighboring block of the firstsub-block in the reference picture may be derived as (DW−1, LH−1).Alternatively, when the left height of the first sub-block is LH and thelower width of the first sub-block is DW, and the x component of thetop-left sample position of the target block is 0 and the y component is0, the location of the temporal neighboring block of the first sub-blockin the reference picture may be derived as (DW−1, LH−1).

Meanwhile, when the target block is split into the second type, thesecond sub-block is adjacent to the bottom-right neighboring block ofthe target block in the reference picture unlike the first sub-block,and as a result, the motion information of the bottom-right neighboringblock of the target block in the reference picture may be used as themotion information candidate for predicting the second sub-block. Thatis, the block at the location of the bottom-right neighboring block ofthe corresponding block in the reference picture may be derived as thetemporal neighboring block of the second sub-block and the motioninformation of the temporal neighboring block may be included as thetemporal motion information candidate of the merge candidate list or theMVP candidate list. For example, when the right height of the secondsub-block is RH, and the x component of the top-left sample position ofthe second sub-block is 0 and the y component is 0, the location of thetemporal neighboring block of the second sub-block in the referencepicture may be derived as (0, RH). Alternatively, when the size of thetarget block is N×N, and the x component of the top-left sample positionof the target block is 0 and the y component is 0, the location of thetemporal neighboring block of the second sub-block in the referencepicture may be derived as (N, N).

Further, as another example, as illustrated in FIG. 9A(c), the targetblock may be split into a third type. The third type may represent atype in which the second sub-block has the triangular shape and is splitto include the top-right sample of the target block. Further, the thirdtype may represent a type in which the split boundary crosses the upperboundary and the right boundary of the target block. When the targetblock is split into the third type, the first sub-block is adjacent tothe bottom-right neighboring block of the target block in the referencepicture, and as a result, the motion information of the bottom-rightneighboring block of the target block in the reference picture may beused as the motion information candidate for predicting the firstsub-block. That is, the block at the location of the bottom-rightneighboring block of the corresponding block in the reference picturemay be derived as the temporal neighboring block of the first sub-blockand the motion information of the temporal neighboring block may beincluded as the temporal motion information candidate of the mergecandidate list or the MVP candidate list. For example, when the leftheight of the first sub-block is LH and the lower width of the firstsub-block is DW, and the x component of the top-left sample position ofthe first sub-block is 0 and the y component is 0, the location of thetemporal neighboring block of the first sub-block in the referencepicture may be derived as (DW, LH). Alternatively, when the size of thetarget block is N×N, and the x component of the top-left sample positionof the target block is 0 and the y component is 0, the location of thetemporal neighboring block of the first sub-block in the referencepicture may be derived as (N, N).

Further, when the target block is split into the third type, the motioninformation of the corresponding block corresponding to the bottom-rightneighboring block of the second sub-block in the reference pictureinstead of the corresponding block corresponding to the bottom-rightneighboring block of the target block in the reference picture may beused as the motion information candidate for predicting the secondsub-block. That is, the block at the location of the bottom-rightneighboring block of the second sub-block in the reference picture maybe derived as the temporal neighboring block of the second sub-block andthe motion information of the temporal neighboring block may be includedas the temporal motion information candidate of the merge candidate listor the MVP candidate list. For example, although not illustrated in thefigure, when the upper height of the second sub-block is RH and theupper width of the second sub-block is UW, and the x component of thetop-left sample position of the second sub-block is 0 and the ycomponent is 0, the location of the temporal neighboring block of thesecond sub-block in the reference picture may be derived as (UW−1,RH−1). Alternatively, when the size of the target block is N×N, theright height of the second sub-block is RH, and the x component of thetop-left sample position of the target block is 0 and the y component is0, the location of the temporal neighboring block of the secondsub-block in the reference picture may be derived as (N−1, RH−1).Alternatively, the temporal neighboring block of the target block may beused as the temporal neighboring block of the second sub-block. Forexample, when the size of the target block is N×N, and the x componentof the top-left sample position of the target block is 0 and the ycomponent is 0, the location of the temporal neighboring block of thesecond sub-block in the reference picture may be derived as (N, N) asillustrated in FIG. 9A(c).

Further, as another example, as illustrated in FIG. 9A(d), the targetblock may be split into a fourth type. The fourth type may represent atype in which the first sub-block has the triangular shape and is splitto include the bottom-left sample of the target block. Further, thefourth type may represent a type in which the split boundary crosses theleft boundary and the lower boundary of the target block. When thetarget block is split into the fourth type, the motion information ofthe corresponding block corresponding to the bottom-right neighboringblock of the first sub-block in the reference picture instead of thecorresponding block corresponding to the bottom-right neighboring blockof the target block in the reference picture may be used as the motioninformation candidate for predicting the first sub-block. That is, theblock at the location of the bottom-right neighboring block of the firstsub-block in the reference picture may be derived as the temporalneighboring block of the first sub-block and the motion information ofthe temporal neighboring block may be included as the temporal motioninformation candidate of the merge candidate list or the MVP candidatelist. For example, when the left height of the first sub-block is LH andthe lower width of the first sub-block is DW, and the x component of thetop-left sample position of the first sub-block is 0 and the y componentis 0, the location of the temporal neighboring block of the firstsub-block in the reference picture may be derived as (DW−1, LH−1).Alternatively, when the lower width of the first sub-block is DW and thesize of the target block is N×N, and the x component of the top-leftsample position of the target block is 0 and the y component is 0, thelocation of the temporal neighboring block of the first sub-block in thereference picture may be derived as (DW−1, N−1).

Meanwhile, when the target block is split into the fourth type, thesecond sub-block is adjacent to the bottom-right neighboring block ofthe target block in the reference picture unlike the first sub-block,and as a result, the motion information of the bottom-right neighboringblock of the target block in the reference picture may be used as themotion information candidate for predicting the second sub-block. Thatis, the block at the location of the bottom-right neighboring block ofthe corresponding block in the reference picture may be derived as thetemporal neighboring block of the second sub-block and the motioninformation of the temporal neighboring block may be included as thetemporal motion information candidate of the merge candidate list or theMVP candidate list. For example, when the right height of the secondsub-block is RH and the upper width of the second sub-block is UW, andthe x component of the top-left sample position of the second sub-blockis 0 and the y component is 0, the location of the temporal neighboringblock of the second sub-block in the reference picture may be derived as(UW, RH). Alternatively, when the upper height of the second sub-blockis RH and the upper width of the second sub-block is UW, and the xcomponent of the top-left sample position of the target block is 0 andthe y component is 0, the location of the temporal neighboring block ofthe second sub-block in the reference picture may be derived as (UW,RH). Alternatively, when the size of the target block is N×N, and the xcomponent of the top-left sample position of the target block is 0 andthe y component is 0, the location of the second sub-block in thereference picture may be derived as (N, N).

Further, as another example, as illustrated in FIG. 9B(e), the targetblock may be split into a fifth type. The fifth type may represent atype in which the first sub-block and the second sub-block have arectangular shape and the left boundary of the first sub-block and theright height of the second sub-block are split to be the same as theheight of the target block. Alternatively, the fifth type may representa type in which the split boundary of the target block is split to be incontact with the upper boundary and the lower boundary of the targetblock.

When the target block is split into the fifth type, the motioninformation of the corresponding block corresponding to the bottom-rightneighboring block of the first sub-block in the reference pictureinstead of the corresponding block corresponding to the bottom-rightneighboring block of the target block in the reference picture may beused as the motion information candidate for predicting the firstsub-block. That is, the block at the location of the bottom-rightneighboring block of the first sub-block in the reference picture may bederived as the temporal neighboring block of the first sub-block and themotion information of the temporal neighboring block may be included asthe temporal motion information candidate of the merge candidate list orthe MVP candidate list. For example, when the left height of the firstsub-block is LH and the lower width of the first sub-block is DW, andthe x component of the top-left sample position of the first sub-blockis 0 and the y component is 0, the location of the temporal neighboringblock of the first sub-block in the reference picture may be derived as(DW−1, LH−1). Alternatively, when the lower width of the first sub-blockis DW and the size of the target block is N×N, and the x component ofthe top-left sample position of the target block is 0 and the ycomponent is 0, the location of the temporal neighboring block of thefirst sub-block in the reference picture may be derived as (DW−1, N−1).

Meanwhile, when the target block is split into the fifth type, thesecond sub-block is adjacent to the bottom-right neighboring block ofthe target block in the reference picture unlike the first sub-block,and as a result, the motion information of the bottom-right neighboringblock of the target block in the reference picture may be used as themotion information candidate for predicting the second sub-block. Thatis, the block at the location of the bottom-right neighboring block ofthe corresponding block in the reference picture may be derived as thetemporal neighboring block of the second sub-block and the motioninformation of the temporal neighboring block may be included as thetemporal motion information candidate of the merge candidate list or theMVP candidate list. For example, when the right height of the secondsub-block is RH and the upper width of the second sub-block is UW, andthe x component of the top-left sample position of the second sub-blockis 0 and the y component is 0, the location of the temporal neighboringblock of the second sub-block in the reference picture may be derived as(UW, RH). Alternatively, when the right height of the second sub-blockis RH, the size of the target block is N×N, and the x component of thetop-left sample position of the target block is 0 and the y component is0, the location of the temporal neighboring block of the secondsub-block in the reference picture may be derived as (N, RH).Alternatively, when the size of the target block is N×N, and the xcomponent of the top-left sample position of the target block is 0 andthe y component is 0, the location of the second sub-block in thereference picture may be derived as (N, N).

Further, as another example, as illustrated in FIG. 9B(f), the targetblock may be split into a sixth type. The sixth type may represent atype in which the first sub-block and the second sub-block have therectangular shape and the upper boundary of the first sub-block and thelower width of the second sub-block are split to be the same as thewidth of the target block. Alternatively, the sixth type may represent atype in which the split boundary of the target block is split to be incontact with the left boundary and the right boundary of the targetblock.

When the target block is split into the sixth type, the motioninformation of the corresponding block corresponding to the bottom-rightneighboring block of the first sub-block in the reference pictureinstead of the corresponding block corresponding to the bottom-rightneighboring block of the target block in the reference picture may beused as the motion information candidate for predicting the firstsub-block. That is, the block at the location of the bottom-rightneighboring block of the first sub-block in the reference picture may bederived as the temporal neighboring block of the first sub-block and themotion information of the temporal neighboring block may be included asthe temporal motion information candidate of the merge candidate list orthe MVP candidate list. For example, when the left height of the firstsub-block is LH, and the x component of the top-left sample position ofthe first sub-block is 0 and the y component is 0, the location of thetemporal neighboring block of the first sub-block in the referencepicture may be derived as (0, LH−1). Alternatively, when the left heightof the first sub-block is LH, and the x component of the top-left sampleposition of the target block is 0 and the y component is 0, the locationof the temporal neighboring block of the first sub-block in thereference picture may be derived as (0, LH−1).

Meanwhile, when the target block is split into the sixth type, thesecond sub-block is adjacent to the bottom-right neighboring block ofthe target block in the reference picture unlike the first sub-block,and as a result, the motion information of the bottom-right neighboringblock of the target block in the reference picture may be used as themotion information candidate for predicting the second sub-block. Thatis, the block at the location of the bottom-right neighboring block ofthe corresponding block in the reference picture may be derived as thetemporal neighboring block of the second sub-block and the motioninformation of the temporal neighboring block may be included as thetemporal motion information candidate of the merge candidate list or theMVP candidate list. For example, when the right height of the secondsub-block is RH, and the x component of the top-left sample position ofthe second sub-block is 0 and the y component is 0, the location of thetemporal neighboring block of the second sub-block in the referencepicture may be derived as (0, RH). Alternatively, when the size of thetarget block is N×N, and the x component of the top-left sample positionof the target block is 0 and the y component is 0, the location of thesecond sub-block in the reference picture may be derived as (N, N).

Meanwhile, when the target block is split through the GP structure asdescribed above, discontinuity between the first sub-block and thesecond sub-block of the target block may occur. That is, prediction ofeach of the first sub-block and the second sub-block may be separatelyperformed, and as a result, a problem that the boundary between thefirst sub-block and the second sub-block is shown may occur. The presentdisclosure proposes a method for performing overlapped motioncompensation between the first sub-block and the second sub-block inorder to remove the discontinuity between the first sub-block and thesecond sub-block split through the GP structure.

FIG. 10 exemplarily illustrates a boundary region between a firstsub-block and a second sub-block split through the GP structure.Referring to FIG. 10, the target block may be split into the firstsub-block and the second sub-block through the GP structure. In otherwords, the target block may be split into the first sub-block and thesecond sub-block based on the split boundary. In this case, a boundaryregion 1010 of the first sub-block may represent a region which isincluded in the first sub-block and is adjacent to the second sub-block.Further, a boundary region 1020 of the second sub-block may represent aregion which is included in the second sub-block and is adjacent to thefirst sub-block. The overlapped motion compensation may be performed forsamples of the boundary region of the first sub-block and the boundaryregion of the second sub-block. That is, the boundary region of thefirst sub-block and the boundary region of the second sub-block may bederived as a region in which the overlapped motion compensation isperformed.

FIG. 11 may exemplarily illustrate samples for which filtering foroverlapped motion compensation is performed. P0 and P1 illustrated inFIG. 11 may represent samples included in the boundary region of thefirst sub-block and Q0 and Q1 may represent samples included in theboundary region of the second sub-block. In this case, filtering may beperformed for the P0 and/or the P1 for the overlapped motioncompensation. Alternatively, filtering may be performed for the Q0and/or the Q1 for the overlapped motion compensation. In other words, inorder to remove the discontinuity between the first sub-block and thesecond sub-block, filtering may be performed for the P0 and/or the P1 orfiltering may be performed for the Q0 and/or the Q1.

For example, the filtering may be performed for a sample adjacent to thesecond sub-block among the samples of the first sub-block and a sampleadjacent to the first sub-block among the samples of the secondsub-block. That is, the filtering may be performed for the P0 and the Q0illustrated in FIG. 11 above. Specifically, sample value 1 of the P0 maybe derived based on the motion information of the first sub-block,sample value 2 of the P0 may be derived based on the motion informationof the second sub-block, and a filtered sample value of the P0 may bederived based on the sample value 1 and the sample value 2 of the P0.Further, sample value 1 of the Q0 may be derived based on the motioninformation of the first sub-block, sample value 2 of the Q0 may bederived based on the motion information of the second sub-block, and afiltered sample value of the Q0 may be derived based on the sample value1 and the sample value 2 of the Q0.

In this case, the filtered value of the P0 and the filtered value of theQ0 may be derived through the following equation.

P0=(3*P0_(Part0) +P0_(Part1))/4

Q0=(Q0_(Part0)+3*Q0_(Part1))/4  [Equation 1]

Here, P0 _(Part0) may represent the sample value 1 of the P0 based onthe motion information of the first sub-block, P0 _(Part1) may representthe sample value 2 of the P0 based on the motion information of thesecond sub-block, and P0 may represent the filtered sample value of theP0. Further, Q0 _(Part0) may represent the sample value 1 of the Q0based on the motion information of the first sub-block, Q0 _(Part1) mayrepresent the sample value 2 of the Q0 based on the motion informationof the second sub-block, and Q0 may represent the filtered sample valueof the Q0.

Alternatively, the value of the P0 and the filtered value of the Q0 maybe derived through the following equation.

P0=(7*P0_(Part0) +P0_(Part1))/8

Q0=(Q0_(Part0)+7*Q0_(Part1))/8  [Equation 2]

Here, P0 _(Part0) may represent the sample value 1 of the P0 based onthe motion information of the first sub-block, P0 _(Part1) may representthe sample value 2 of the P0 based on the motion information of thesecond sub-block, and P0 may represent the filtered sample value of theP0. Further, Q0 _(Part0) may represent the sample value 1 of the Q0based on the motion information of the first sub-block, Q0 _(Part1) mayrepresent the sample value 2 of the Q0 based on the motion informationof the second sub-block, and Q0 may represent the filtered sample valueof the Q0.

Further, as another example, the filtering may be performed for a firstsample adjacent to the second sub-block and a second sample adjacent tothe left side of the first sample among the samples of the firstsub-block and the filtering may be performed for a first sample adjacentto the first sub-block and a second sample adjacent to the right side ofthe first sample among the samples of the second sub-block.Alternatively, the filtering may be performed for the first sampleadjacent to the second sub-block and the second sample adjacent to theupper side of the first sample among the samples of the first sub-blockand the filtering may be performed for the first sample adjacent to thefirst sub-block and the second sample adjacent to the lower side of thefirst sample among the samples of the second sub-block. Two samples ofthe first sub-block around the split boundary may be included in theboundary region of the first sub-block and two samples of the secondsub-block around the split boundary may be included in the boundaryregion of the second sub-block. In this case, the filtering may beperformed for the P0 and the P1, and the Q0 and the Q1 illustrated inFIG. 11 above. Specifically, sample value 1 of the P0 may be derivedbased on the motion information of the first sub-block, sample value 2of the P0 may be derived based on the motion information of the secondsub-block, and a filtered sample value of the P0 may be derived based onthe sample value 1 and the sample value 2 of the P0. Further, samplevalue 1 of the P1 may be derived based on the motion information of thefirst sub-block, sample value 2 of the P1 may be derived based on themotion information of the second sub-block, and a filtered sample valueof the P1 may be derived based on the sample value 1 and the samplevalue 2 of the P1. Further, sample value 1 of the Q0 may be derivedbased on the motion information of the first sub-block, sample value 2of the Q0 may be derived based on the motion information of the secondsub-block, and a filtered sample value of the Q0 may be derived based onthe sample value 1 and the sample value 2 of the Q0. Further, samplevalue 1 of the Q1 may be derived based on the motion information of thefirst sub-block, sample value 2 of the Q1 may be derived based on themotion information of the second sub-block, and a filtered sample valueof the Q1 may be derived based on the sample value 1 and the samplevalue 2 of the Q1.

In this case, the filtered value of the P0, the filtered value of theP1, the filtered value of the Q0, and the filtered value of the Q1 maybe derived through the following equation.

P0=(3*P0_(Part0) +P0_(Part1))/4

P1=(7*P1_(Part0) +P1_(Part1))/8

Q0=(Q0_(Part0)+3*Q0_(Part1))/4

Q1=(Q1_(Part0)+7*Q1_(Part1))/8  [Equation 3]

Here, P0 _(Part0) may represent the sample value 1 of the P0 based onthe motion information of the first sub-block, P0 _(Part1) may representthe sample value 2 of the P0 based on the motion information of thesecond sub-block, and P0 may represent the filtered sample value of theP0. Here, P1 _(Part0) may represent the sample value 1 of the P1 basedon the motion information of the first sub-block, P1 _(Part1) mayrepresent the sample value 2 of the P1 based on the motion informationof the second sub-block, and P1 may represent the filtered sample valueof the P1. Further, Q0 _(Part0) may represent the sample value 1 of theQ0 based on the motion information of the first sub-block, Q0 _(Part1)may represent the sample value 2 of the Q0 based on the motioninformation of the second sub-block, and Q0 may represents the filteredsample value of the Q0. Further, Q1 _(Part0) may represent the samplevalue 1 of the Q1 based on the motion information of the firstsub-block, Q1 _(Part1) may represent the sample value 2 of the Q1 basedon the motion information of the second sub-block, and Q1 may representsthe filtered sample value of the Q1.

The number of samples around the split boundary in which the filteringis performed may be variably selected in units of slice or block.Alternatively, the number of samples around the split boundary in whichthe filtering is performed may be selected based on the size of thetarget block. For example, when the target block is a 16×16 sized block,the filtering may be applied to one sample around the split boundaryamong samples of a sub-block of the target block. For example, when thetarget block is a block larger than the 16×16 sized block, the filteringmay be applied to two samples around the split boundary among thesamples of the sub-block of the target block. Meanwhile, informationindicating whether to apply the filtering may be transmitted in units ofsequence parameter set (SPS), picture parameter set (PSP), slice, block,and the like.

Meanwhile, when the target block is split based on the GP structure, atransformation process for the target block may be performed throughvarious methods.

As an example, a method for performing one transformation andquantization process for the first sub-block and the second sub-blockmay be proposed. Specifically, prediction for each of the firstsub-block and the second sub-block derived by splitting the target blockbased on the GP structure may be performed, a residual signal for eachof the first sub-block and the second sub-block may be performed, andencoded information of the first sub-block and the second sub-blockderived by performing one transformation, quantization, and entropyencoding for the residual signal of the first sub-block and the residualsignal of the second sub-block may be transmitted to the decodingapparatus. In other words, the encoding apparatus may perform onetransformation and quantization process for the first sub-block and thesecond sub-block, and entropy-encode information on the first sub-blockand the second sub-block generated through the transformation andquantization process and transmit the entropy-encoded information to thedecoding apparatus.

FIG. 12 illustrates an example of a first sub-block and a secondsub-block for which one transform process is performed. Separateprediction may be performed for the first sub-block and the secondsub-block. The residual signal for the first sub-block may be generatedbased on predicted samples of the first sub-block generated through theprediction of the first sub-block and the residual signal for the secondsub-block may be generated based on predicted samples of the secondsub-block generated through the prediction of the second sub-block. Inthis case, as illustrated in FIG. 12, the residual signal of the firstsub-block and the residual signal of the second sub-block may becombined into one block and the transformation and quantization processfor the combined block may be performed.

Further, as another example, a method for performing a separatetransformation and quantization process for the first sub-block and thesecond sub-block may be proposed.

FIG. 13 illustrates an example of the first sub-block and the secondsub-block for which a separate transform process is performed. FIG. 13Amay illustrate the residual signal of the first sub-block which istransformed and FIG. 13B may illustrate the residual signal of thesecond sub-block which is transformed. Prediction for each of the firstsub-block and the second sub-block derived by splitting the target blockbased on the GP structure may be performed, a residual signal for eachof the first sub-block and the second sub-block may be performed, andencoded information of the first sub-block and encoded information ofthe second sub-block may be derived and transmitted to the decodingapparatus by performing one transformation, quantization, and entropyencoding for each of the residual signal of the first sub-block and theresidual signal of the second sub-block. In other words, the encodingapparatus may perform the separate transformation and quantizationprocess for each of the residual signal of the first sub-block and theresidual signal of the second sub-block, and entropy-encode informationon the first sub-block and the second sub-block generated through thetransformation and quantization process and transmit the entropy-encodedinformation to the decoding apparatus.

Further, as another example, only the first sub-block of the firstsub-block and the second sub-block may be transformed. That is, only theresidual signal of the first sub-block may be transformed. In this case,the residual signal of the first sub-block may be transformed based on atransform kernel having a smallest size, which includes only the firstsub-block. That is, the transform kernel may represent the transformkernel having the smallest size among transform kernels having sizesincluding the size of the first sub-block.

Alternatively, as illustrated in FIG. 13C, the residual signal of thefirst sub-block is transformed based on the transform kernel having thesize of the target block, but a region not included in the firstsub-block among the regions of the target block, i.e., the secondsub-block region is filled with a value of 0 to be transformed. In otherwords, the second sub-block region padded with 0 is combined to theresidual signal of the first sub-block to derive the block having thetarget block size and the derived block may be transformed based on thetransform kernel having the target block size.

Alternatively, as illustrated in FIG. 13D, the residual signal of thefirst sub-block may be rearranged and the rearranged residual signal maybe transformed. Specifically, as illustrated in FIG. 13D, a residualsignal of an a region 1310 of the first sub-block may be rearranged to ab region 1320 of the first sub-block and the rearranged residual signalmay be transformed. That is, the residual signal of the a region 1310may be rearranged in the b region 1320 and the residual signal of thefirst sub-block may have the rectangular shape and the residual signalof the first sub-block may be transformed based on the transform kernelhaving the size including the first sub-block rearranged.

FIG. 14 schematically illustrates a video encoding method by an encodingapparatus according to the present disclosure. The method disclosed inFIG. 14 may be performed by the encoding apparatus disclosed in FIG. 1.Specifically, for example, S1400 of FIG. 14 may be performed by apicture partitioner of the encoding apparatus, S1410 and S1420 may beperformed by a predictor of the encoding apparatus, and S1430 may beperformed by an entropy encoder of the encoding apparatus.

The encoding apparatus splits a target block into a first sub-block anda second sub-block (S1400). The target block may be a block split in aquad-tree (QT) structure and a block of a terminal node in the QTstructure, which is no longer split in the QT structure. The terminalnode may also be referred to as a leaf node. Here, the QT structure mayrepresent a structure in which a 2N×2N sized target block is split intofour N×N sized sub-blocks. In this case, the target block may be splitin a geometry partition (GP) structure and the GP structure mayrepresent a structure in which the target block is split into varioustypes of sub-blocks. Further, the GP structure may represent a structurein which the target block is split based on a predetermined splitboundary.

The encoding apparatus may derive the split boundary and split thetarget block into the first sub-block and the second sub-block based onthe split boundary. In other words, the target block may be split intothe first sub-block and the second sub-block through the split boundary.

In this case, the encoding apparatus may generate split information forthe target block. The split information may be referred to as GP splitinformation. The split information may include information indicating anangle of the split boundary and information indicating a distancebetween the split boundary and a center of the target block.Alternatively, the split information may include a GP split indexindicating one of a plurality of predetermined split types. In thiscase, the target block may be split into the first sub-block and thesecond sub-block of the type indicated by the GP split index. Meanwhile,the first sub-block may represent a block positioned at a left sideamong the blocks split from the target block and the second sub-blockmay represent a block positioned at a right side among the blocks splitfrom the target block. Further, the first sub-block and the secondsub-block may be non-rectangular blocks.

Further, the split information for the target block may include ageometry partition (GP) split flag for the target block and the GP splitflag may indicate whether the target block is split into sub-blockshaving various forms. Alternatively, the GP split flag may indicatewhether the target block is split into sub-blocks through apredetermined split boundary. When the value of the GP split flag is 1,i.e., when the GP split flag indicates that the target block is splitinto the sub-blocks, the target block may be split into a firstsub-block and a second sub-block through a split boundary derived basedon information indicating the angle of the split boundary and/orinformation indicating a distance between the split boundary and thecenter of the target block.

The encoding apparatus derives a first motion information candidate listfor the first sub-block and a second motion information candidate listfor the second sub-block based on the split type of the target block(S1410). The encoding apparatus may derive the first motion informationcandidate list and the second motion information candidate list based onthe split type of the target block. That is, a spatial neighboring blockand/or a temporal neighboring block of the first sub-block may bederived according to the split type and the spatial neighboring blockand/or the temporal neighboring block of the second sub-block may bederived. The first motion information candidate list may include aspatial candidate indicating motion information of the spatialneighboring block of the first sub-block and/or a temporal candidateindicating motion information of the temporal neighboring block of thefirst sub-block. That is, the first motion information candidate listfor the first sub-block may be different from the second motioninformation candidate list for the second sub-block. A left height or aright height of the first sub-block may be equal to or smaller than aheight of the target block and an upper width or a lower width of thefirst sub-block may be equal to or smaller than a width of the targetblock. Further, the left height or right height of the second sub-blockmay be equal to or smaller than the height of the target block and theupper width or lower width of the second sub-block may be equal to orsmaller than the width of the target block.

Meanwhile, when a merge mode is applied to the first sub-block, thefirst motion information candidate list may represent a merge candidatelist and when a motion vector prediction (MVP) mode is applied to thefirst sub-block, the first motion information candidate list mayrepresent an MVP candidate list. Further, the second motion informationcandidate list may include the spatial candidate indicating the motioninformation of the spatial neighboring block of the second sub-blockand/or the temporal candidate indicating the motion information of thetemporal neighboring block of the second sub-block. Meanwhile, when themerge mode is applied to the second sub-block, the second motioninformation candidate list may represent the merge candidate list andwhen the motion vector prediction (MVP) mode is applied to the secondsub-block, the second motion information candidate list may representthe MVP candidate list.

Meanwhile, the split types derived based on the split information mayinclude six first to sixth types.

For example, the first type may represent a type in which the firstsub-block has the triangular shape and is split to include the top-leftsample of the target block. Further, the first type may represent a typein which the split boundary crosses the upper boundary and the leftboundary of the target block.

When the target block is split into the first type, i.e., the splitboundary crosses the upper boundary and the left boundary of the targetblock, the upper width of the first sub-block is UW, the left height ofthe first sub-block is LH, and an x component of the top-left sampleposition of the first sub-block is 0 and a y component is 0, the firstmotion information candidate list may include a first spatial candidateindicating motion information of a first spatial neighboring block, asecond spatial candidate indicating motion information of a secondspatial neighboring block, a third spatial candidate indicating motioninformation of a third spatial neighboring block, and/or a fourthspatial candidate indicating motion information of a fourth spatialneighboring block. In this case, a location of the first spatialneighboring block may be (−1, LH), the location of the second spatialneighboring block may be (−1, LH−1), the location of the third spatialneighboring block may be (UW, −1), and the location of the fourthspatial neighboring block may be (UW−1, −1). Further, the first motioninformation candidate list may include a temporal candidate indicatingmotion information of the temporal neighboring block in a co-locatedpicture. In this case, the location of the temporal neighboring blockmay be (0, LH−1).

Further, when the target block is split into the first type, i.e., thesplit boundary crosses the upper boundary and the left boundary of thetarget block, the upper width of the first sub-block is UW, the leftheight of the first sub-block is LH, and an x component of the top-leftsample position of the target block is 0 and a y component is 0, thefirst motion information candidate list may include a first spatialcandidate indicating motion information of a first spatial neighboringblock, a second spatial candidate indicating motion information of asecond spatial neighboring block, a third spatial candidate indicatingmotion information of a third spatial neighboring block, and/or a fourthspatial candidate indicating motion information of a fourth spatialneighboring block. In this case, a location of the first spatialneighboring block may be (−1, LH), the location of the second spatialneighboring block may be (−1, LH−1), the location of the third spatialneighboring block may be (UW, −1), and the location of the fourthspatial neighboring block may be (UW−1, −1). Further, the first motioninformation candidate list may include a temporal candidate indicatingmotion information of the temporal neighboring block in a co-locatedpicture. In this case, the location of the temporal neighboring blockmay be (0, LH−1).

Further, when the target block is split into the first type, i.e., thesplit boundary crosses the upper boundary and the left boundary of thetarget block, the upper width of the second sub-block is UW, and the xcomponent of the top-left sample position of the second sub-block is 0and the y component is 0, the second motion information candidate listmay include the spatial candidate indicating the motion information ofthe spatial neighboring block. In this case, the location of the spatialneighboring block may be (−1, −1).

Further, when the target block is split into the first type, i.e., thesplit boundary crosses the upper boundary and the left boundary of thetarget block, the upper width of the second sub-block is UW, the size ofthe target block is N×N, and the x component of the top-left sampleposition of the second sub-block is 0 and the y component is 0, thesecond motion information candidate list may include the spatialcandidate indicating the motion information of the spatial neighboringblock. In this case, the location of the spatial neighboring block maybe (N−UW−1, −1).

As another example, the second type may represent a type in which thesecond sub-block has the triangular shape and is split to include thebottom-right sample of the target block. Further, the second type mayrepresent a type in which the split boundary crosses the right boundaryand the lower boundary of the target block.

When the target block is split into the second type, i.e., the splitboundary crosses the right boundary and the lower boundary of the targetblock, the lower width of the second sub-block is DW, the right heightof the second sub-block is RH, and the x component of the top-leftsample position of the second sub-block is 0 and the y component is 0,the second motion information candidate list may include a first spatialcandidate indicating motion information of a first spatial neighboringblock, a second spatial candidate indicating motion information of asecond spatial neighboring block, a third spatial candidate indicatingmotion information of a third spatial neighboring block, and/or a fourthspatial candidate indicating motion information of a fourth spatialneighboring block. In this case, the location of the first spatialneighboring block may be (−DW, RH), the location of the second spatialneighboring block may be (−DW, RH−1), the location of the third spatialneighboring block may be (−1, −1), and the location of the fourthspatial neighboring block may be (0, −1). Further, the first motioninformation candidate list may include a temporal candidate indicatingmotion information of the temporal neighboring block in the co-locatedpicture. In this case, the location of the temporal neighboring blockmay be (0, LH).

Further, when the target block is split into the second type, i.e., thesplit boundary crosses the right boundary and the lower boundary of thetarget block, the lower width of the second sub-block is DW, the rightheight of the second sub-block is RH, the size of the target block isN×N, and the x component of the top-left sample position of the targetblock is 0 and the y component is 0, the second motion informationcandidate list may include a first spatial candidate indicating motioninformation of a first spatial neighboring block, a second spatialcandidate indicating motion information of a second spatial neighboringblock, a third spatial candidate indicating motion information of athird spatial neighboring block, and/or a fourth spatial candidateindicating motion information of a fourth spatial neighboring block. Inthis case, the location of the first spatial neighboring block may be(N−1−DW, N), the location of the second spatial neighboring block may be(N−1−DW, N−1), the location of the third spatial neighboring block maybe (N, N−1−RH), and the location of the fourth spatial neighboring blockmay be (N−1, N−1−RH). Further, the second motion information candidatelist may include a temporal candidate indicating motion information ofthe temporal neighboring block in the co-located picture. In this case,the location of the temporal neighboring block may be (N, N).

Further, when the target block is split into the second type, i.e., thesplit boundary crosses the right boundary and the lower boundary of thetarget block, the left height of the first sub-block is LH, the lowerwidth of the first sub-block is DW, and the x component of the top-leftsample position of the first sub-block is 0 and the y component is 0,the first motion information candidate list may include the spatialcandidate indicating the motion information of the spatial neighboringblock in the co-located picture. In this case, the location of thetemporal neighboring block may be (DW−1, LH−1).

Further, when the target block is split into the second type, i.e., thesplit boundary crosses the right boundary and the lower boundary of thetarget block, the left height of the first sub-block is LH, the lowerwidth of the first sub-block is DW, and the x component of the top-leftsample position of the target block is 0 and the y component is 0, thefirst motion information candidate list may include the temporalcandidate indicating the motion information of the temporal neighboringblock in the co-located picture. In this case, the location of thetemporal neighboring block may be (DW−1, LH−1).

As another example, the third type may represent a type in which thesecond sub-block has the triangular shape and is split to include thetop-right sample of the target block. Further, the third type mayrepresent a type in which the split boundary crosses the upper boundaryand the right boundary of the target block.

Further, when the target block is split into the third type, i.e., thesplit boundary crosses the upper boundary and the right boundary of thetarget block, the upper width of the first sub-block is UW, and the xcomponent of the top-left sample position of the first sub-block is 0and the y component is 0, the first motion information candidate listmay include a first spatial candidate indicating the motion informationof the first spatial neighboring block and a second spatial candidateindicating the motion information of the second spatial neighboringblock. In this case, the location of the first spatial neighboring blockmay be (UW, −1) and the location of the second spatial neighboring blockmay be (UW−1, −1).

Further, when the target block is split into the third type, i.e., thesplit boundary crosses the upper boundary and the right boundary of thetarget block, the upper width of the first sub-block is UW, and the xcomponent of the top-left sample position of the target block is 0 andthe y component is 0, the first motion information candidate list mayinclude a first spatial candidate indicating the motion information ofthe first spatial neighboring block and a second spatial candidateindicating the motion information of the second spatial neighboringblock. In this case, the location of the first spatial neighboring blockmay be (UW, −1) and the location of the second spatial neighboring blockmay be (UW−1, −1).

Further, when the target block is split into the third type, i.e., thesplit boundary crosses the upper boundary and the right boundary of thetarget block, and the x component of the top-left sample position of thesecond sub-block is 0 and the y component is 0, the second motioninformation candidate list may include the spatial candidate indicatingthe motion information of the spatial neighboring block. In this case,the location of the spatial neighboring block may be (−1, −1). Further,the second motion information candidate list may include a temporalcandidate indicating motion information of the temporal neighboringblock in the co-located picture. For example, when the target block issplit into the third type, i.e., the split boundary crosses the upperboundary and the right boundary of the target block, the upper width ofthe second sub-block is UW, the right height of the second sub-block isRH, the size of the target block is N×N, and the x component of thetop-left sample position of the second sub-block is 0 and the ycomponent is 0, the location of the temporal neighboring block may be(UW, N). Meanwhile, the location of the temporal neighboring block maybe (UW−1, RH−1).

Further, when the target block is split into the third type, i.e., thesplit boundary crosses the upper boundary and the right boundary of thetarget block, the upper width of the second sub-block is UW, the size ofthe target block is N×N, and the x component of the top-left sampleposition of the second sub-block is 0 and the y component is 0, thesecond motion information candidate list may include the spatialcandidate indicating the motion information of the spatial neighboringblock. In this case, the location of the spatial neighboring block maybe (N−1−UW, −1). Further, the second motion information candidate listmay include a temporal candidate indicating motion information of thetemporal neighboring block in the co-located picture. For example, whenthe target block is split into the third type, i.e., the split boundarycrosses the upper boundary and the right boundary of the target block,the right height of the second sub-block is RH, the size of the targetblock is N×N, and the x component of the top-left sample position of thetarget block is 0 and the y component is 0, the location of the temporalneighboring block may be (N, N). Meanwhile, the location of the temporalneighboring block may be (N−1, RH−1).

As another example, a fourth type may represent a type in which thesecond sub-block has the triangular shape and is split to include thebottom-left sample of the target block. Further, the fourth type mayrepresent a type in which the split boundary crosses the left boundaryand the lower boundary of the target block.

Further, when the target block is split into the fourth type, i.e., thesplit boundary crosses the left boundary and the lower boundary of thetarget block, the upper width of the second sub-block is UW, the lowerwidth of the second sub-block is DW, the right height of the secondsub-block is RH, and the x component of the top-left sample position ofthe second sub-block is 0 and the y component is 0, the second motioninformation candidate list may include a first spatial candidateindicating the motion information of the first spatial neighboring blockand a second spatial candidate indicating the motion information of thesecond spatial neighboring block. In this case, the location of thefirst spatial neighboring block may be (UW−1−DW, RH) and the location ofthe second spatial neighboring block may be (UW−1−DW, RH−1).

Further, when the target block is split into the fourth type, i.e., thesplit boundary crosses the left boundary and the lower boundary of thetarget block, the lower width of the second sub-block is DW, the size ofthe target block is N×N, and the x component of the top-left sampleposition of the target block is 0 and the y component is 0, the secondmotion information candidate list may include a first spatial candidateindicating the motion information of the first spatial neighboring blockand a second spatial candidate indicating the motion information of thesecond spatial neighboring block. In this case, the location of thefirst spatial neighboring block may be (N−1−DW, N) and the location ofthe second spatial neighboring block may be (N−1−DW, N−1).

Further, when the target block is split into the fourth type, i.e., thesplit boundary crosses the left boundary and the lower boundary of thetarget block, the left height of the first sub-block is LH, the lowerwidth of the first sub-block is DW, and the x component of the top-leftsample position of the first sub-block is 0 and the y component is 0,the first motion information candidate list may include the spatialcandidate indicating the motion information of the spatial neighboringblock in the co-located picture. In this case, the location of thetemporal neighboring block may be (DW−1, LH−1).

Further, when the target block is split into the fourth type, i.e., thesplit boundary crosses the left boundary and the lower boundary of thetarget block, the lower width of the first sub-block is DW, the size ofthe target block is N×N, and the x component of the top-left sampleposition of the target block is 0 and the y component is 0, the firstmotion information candidate list may include the temporal candidateindicating the motion information of the temporal neighboring block inthe co-located picture. In this case, the location of the temporalneighboring block may be (DW−1, N−1).

As another example, a fifth type may represent a type in which the firstsub-block and the second sub-block have a rectangular shape and the leftboundary of the first sub-block and the right height of the secondsub-block are split to be the same as the height of the target block.Further, the fifth type may represent a type in which the split boundarycrosses the upper boundary and the lower boundary of the target block.

When the target block is split into the fifth type, i.e., the splitboundary crosses the upper boundary and the lower boundary of the targetblock, the upper width of the first sub-block is UW, and the x componentof the top-left sample position of the first sub-block is 0 and the ycomponent is 0, the first motion information candidate list may includea first spatial candidate indicating the motion information of the firstspatial neighboring block and a second spatial candidate indicating themotion information of the second spatial neighboring block. In thiscase, the location of the first spatial neighboring block may be (UW,−1) and the location of the second spatial neighboring block may be(UW−1, −1). Further, the first motion information candidate list mayinclude a temporal candidate indicating motion information of thetemporal neighboring block in the co-located picture. For example, whenthe target block is split into the fifth type, i.e., the split boundarycrosses the upper boundary and the lower boundary of the target block,the left height of the first sub-block is LH, the lower width of thefirst sub-block is DW, and the x component of the top-left sampleposition of the first sub-block is 0 and the y component is 0, thelocation of the temporal neighboring block may be (DW−1, LH−1).

Further, when the target block is split into the fifth type, i.e., thesplit boundary crosses the upper boundary and the lower boundary of thetarget block, the upper width of the first sub-block is UW, the lowerwidth of the first sub-block is DW, the size of the target block is N×N,and the x component of the top-left sample position of the target blockis 0 and the y component is 0, the first motion information candidatelist may include at least one of a first spatial candidate indicatingthe motion information of the first spatial neighboring block and asecond spatial candidate indicating the motion information of the secondspatial neighboring block, and a temporal candidate indicating themotion information of the temporal neighboring block in the co-locatedpicture. In this case, the location of the first spatial neighboringblock may be (UW, −1) and the location of the second spatial neighboringblock may be (UW−1, −1), and the location of the temporal neighboringblock may be (DW−1, N−1).

Further, when the target block is split into the fifth type, i.e., thesplit boundary crosses the upper boundary and the lower boundary of thetarget block, the upper width of the second sub-block is UW, the lowerwidth of the second sub-block is DW, the right height of the secondsub-block is RH, and the x component of the top-left sample position ofthe second sub-block is 0 and the y component is 0, the second motioninformation candidate list may include at least one of a first spatialcandidate indicating the motion information of the first spatialneighboring block, a second spatial candidate indicating the motioninformation of the second spatial neighboring block, and a third spatialcandidate indicating the motion information of the third spatialneighboring block, and a temporal candidate indicating the motioninformation of the temporal neighboring block in the co-located picture.In this case, the location of the first spatial neighboring block may be(UW−1−DW, RH), the location of the second spatial neighboring block maybe (UW−1−DW, RH−1), the location of the third spatial neighboring blockmay be (−1, −1), and the location of the temporal neighboring block maybe (UW−1, RH−1).

Further, when the target block is split into the fifth type, i.e., thesplit boundary crosses the upper boundary and the lower boundary of thetarget block, the upper width of the second sub-block is UW, the lowerwidth of the first sub-block is DW, the size of the target block is N×N,and the x component of the top-left sample position of the target blockis 0 and the y component is 0, the second motion information candidatelist may include at least one of a first spatial candidate indicatingthe motion information of the first spatial neighboring block, a secondspatial candidate indicating the motion information of the secondspatial neighboring block, and a third spatial candidate indicating themotion information of the third spatial neighboring block, and atemporal candidate indicating the motion information of the temporalneighboring block in the co-located picture. In this case, the locationof the first spatial neighboring block may be (N−1−DW, N), the locationof the second spatial neighboring block may be (N−1−DW, N−1), thelocation of the third spatial neighboring block may be (N−1−UW, −1), andthe location of the temporal neighboring block may be (N, N).

As another example, a sixth type may represent a type in which the firstsub-block and the second sub-block have a rectangular shape and theupper boundary of the first sub-block and the lower width of the secondsub-block are split to be the same as the height of the target block.Further, the sixth type may represent a type in which the split boundarycrosses the left boundary and the right boundary of the target block.

Further, when the target block is split into the sixth type, i.e., thesplit boundary crosses the left boundary and the right boundary of thetarget block, the left height of the first sub-block is LH, and the xcomponent of the top-left sample position of the first sub-block is 0and the y component is 0, the first motion information candidate listmay include a first spatial candidate indicating the motion informationof the first spatial neighboring block and a second spatial candidateindicating the motion information of the second spatial neighboringblock. In this case, the location of the first spatial neighboring blockmay be (−1, LH) and the location of the second spatial neighboring blockmay be (−1, LH−1). Further, the first motion information candidate listmay include a temporal candidate indicating motion information of thetemporal neighboring block in the co-located picture. For example, whenthe target block is split into the sixth type, i.e., the split boundarycrosses the left boundary and the right boundary of the target block,the left height of the first sub-block is LH, and the x component of thetop-left sample position of the first sub-block is 0 and the y componentis 0, the location of the temporal neighboring block may be (0, LH−1).

Further, when the target block is split into the sixth type, i.e., thesplit boundary crosses the left boundary and the right boundary of thetarget block, the left height of the first sub-block is LH, and the xcomponent of the top-left sample position of the target block is 0 andthe y component is 0, the first motion information candidate list mayinclude a first spatial candidate indicating the motion information ofthe first spatial neighboring block and a second spatial candidateindicating the motion information of the second spatial neighboringblock. In this case, the location of the first spatial neighboring blockmay be (−1, LH) and the location of the second spatial neighboring blockmay be (−1, LH−1). Further, the first motion information candidate listmay include a temporal candidate indicating motion information of thetemporal neighboring block in the co-located picture. For example, whenthe target block is split into the sixth type, i.e., the split boundarycrosses the left boundary and the right boundary of the target block,the left height of the first sub-block is LH, and the x component of thetop-left sample position of the target block is 0 and the y component is0, the location of the temporal neighboring block may be (0, LH−1).

Further, when the target block is split into the sixth type, i.e., thesplit boundary crosses the left boundary and the right boundary of thetarget block, the lower width of the second sub-block is DW, the leftheight of the second sub-block is LH, the right height of the secondsub-block is RH, and the x component of the top-left sample position ofthe second sub-block is 0 and the y component is 0, the second motioninformation candidate list may include a first spatial candidateindicating the motion information of the first spatial neighboring blockand a second spatial candidate indicating the motion information of thesecond spatial neighboring block. In this case, the location of thefirst spatial neighboring block may be (DW, LH−1−RH) and the location ofthe second spatial neighboring block may be (DW−1, LH−1−RH).

Further, when the target block is split into the sixth type, i.e., thesplit boundary crosses the left boundary and the right boundary of thetarget block, the right height of the second sub-block is RH, the sizeof the target block is N×N, and the x component of the top-left sampleposition of the target block is 0 and the y component is 0, the secondmotion information candidate list may include a first spatial candidateindicating the motion information of the first spatial neighboring blockand a second spatial candidate indicating the motion information of thesecond spatial neighboring block. In this case, the location of thefirst spatial neighboring block may be (N, N−1−RH) and the location ofthe second spatial neighboring block may be (N−1, N−1−RH).

The encoding apparatus performs inter prediction of the first sub-blockbased on the first motion information candidate list and performs interprediction and encoding of the second sub-block based on the secondmotion information candidate list (S1420). The encoding apparatus mayseparately perform the inter prediction for each of the first sub-blockand the second sub-block. The encoding apparatus may determine a modeapplied to the first sub-block between the merge mode and the motionvector prediction (MVP) mode. Further, the encoding apparatus maydetermine a mode applied to the second sub-block between the merge modeand the motion vector prediction (MVP) mode.

The encoding apparatus may perform inter prediction of the firstsub-block based on the first motion information candidate list.Specifically, the encoding apparatus may perform the motion informationof the first sub-block based on the first motion information candidatelist. For example, when the merge mode is applied to the firstsub-block, the first motion information candidate list may represent amerge candidate list and the motion information of the candidateselected in the first motion information candidate list may be derivedas the motion information of the first sub-block. A candidate suitablefor prediction of the first sub-block may be selected among thecandidates included in the first motion information candidate list.Further, prediction information of the first sub-block may be generatedand the prediction information may include a merge index indicating theselected candidate. The motion information of the first sub-block mayinclude a reference picture index and a motion vector.

The encoding apparatus may perform the inter prediction for the firstsub-block based on the motion information. Specifically, the encodingapparatus may derive a reference block of the first sub-block based onthe motion information. That is, the encoding apparatus may derive areference block indicating the motion vector in the reference pictureindicated by the reference picture index. The encoding apparatus maypredict the first sub-block based on the reference block. That is, theencoding apparatus may derive a reconstructed sample in the referenceblock as a predicted sample of the first sub-block.

Further, for example, when the motion vector prediction (MVP) mode isapplied to the first sub-block, the first motion information candidatelist may represent an MVP candidate list and a motion vector of thecandidate selected in the first motion information candidate list may bederived as a motion vector predictor (MVP) of the first sub-block. Acandidate suitable for prediction of the first sub-block may be selectedamong the candidates included in the first motion information candidatelist. The encoding apparatus may derive the motion vector of the firstsub-block by using the MVP.

Further, the prediction information of the first sub-block may begenerated and the prediction information may include an MVP flagindicating the selected candidate. Further, the prediction informationmay include a motion vector difference (MVD) of the first sub-block.

The encoding apparatus may select the reference picture of the firstsub-block among the reference pictures included in the reference picturelist. The prediction information may include a reference picture indexindicating the reference picture.

The encoding apparatus may perform the inter prediction for the firstsub-block based on the motion information. Specifically, the encodingapparatus may derive the reference block of the first sub-block based onthe motion vector and the reference picture index. That is, the encodingapparatus may derive a reference block indicating the motion vector inthe reference picture indicated by the reference picture index. Theencoding apparatus may predict the first sub-block based on thereference block. That is, the encoding apparatus may derive areconstructed sample in the reference block as a predicted sample of thefirst sub-block.

Further, the encoding apparatus may perform inter prediction of thesecond sub-block based on the second motion information candidate list.Specifically, the encoding apparatus may perform the motion informationof the second sub-block based on the second motion information candidatelist. For example, when the merge mode is applied to the secondsub-block, the second motion information candidate list may represent amerge candidate list and the motion information of the candidateselected in the second motion information candidate list may be derivedas the motion information of the second sub-block. A candidate suitablefor prediction of the second sub-block may be selected among thecandidates included in the second motion information candidate list.Further, prediction information of the second sub-block may be generatedand the prediction information may include a merge index indicating theselected candidate. The motion information of the second sub-block mayinclude the reference picture index and the motion vector.

The encoding apparatus may perform the inter prediction for the secondsub-block based on the motion information. Specifically, the encodingapparatus may derive a reference block of the second sub-block based onthe motion information. That is, the encoding apparatus may derive areference block indicating the motion vector in the reference pictureindicated by the reference picture index. The encoding apparatus maypredict the second sub-block based on the reference block. That is, theencoding apparatus may derive the reconstructed sample in the referenceblock as the predicted sample of the second sub-block.

Further, for example, when the motion vector prediction (MVP) mode isapplied to the second sub-block, the second motion information candidatelist may represent an MVP candidate list and the motion vector of thecandidate selected in the second motion information candidate list maybe derived as the motion vector predictor (MVP) of the second sub-block.A candidate suitable for prediction of the second sub-block may beselected among the candidates included in the second motion informationcandidate list. The encoding apparatus may derive the motion vector ofthe second sub-block by using the MVP.

Further, the prediction information of the second sub-block may begenerated and the prediction information may include the MVP flagindicating the selected candidate. Further, the prediction informationmay include the motion vector difference (MVD) of the second sub-block.

The encoding apparatus may select the reference picture of the secondsub-block among the reference pictures included in the reference picturelist. The prediction information may include the reference picture indexindicating the reference picture.

The encoding apparatus may perform the inter prediction for the secondsub-block based on the motion information. Specifically, the encodingapparatus may derive the reference block of the second sub-block basedon the motion vector and the reference picture index. That is, theencoding apparatus may derive a reference block indicating the motionvector in the reference picture indicated by the reference pictureindex. The encoding apparatus may predict the second sub-block based onthe reference block. That is, the encoding apparatus may derive thereconstructed sample in the reference block as the predicted sample ofthe second sub-block.

Further, the encoding apparatus may perform filtering for a first sampleadjacent to the second sub-block among the samples of the firstsub-block. The filtering may represent overlapped motion compensationfiltering. For example, the encoding apparatus may derive sample value 1of the first sample based on the motion information of the firstsub-block and derive sample value 2 of the first sample based on themotion information of the second sub-block. Next, the encoding apparatusmay derive a sample value of the first sample based on the sample value1 and the sample value 2 of the first sample. For example, the encodingapparatus may derive the sample value of the first sample by weightedsum of the sample value 1 and the sample value 2 of the first sample.Further, the sample value of the first sample may be derived based onEquation 1 described above. Alternatively, the sample value of the firstsample may be derived based on Equation 2 described above.

Further, the encoding apparatus may perform filtering for a first sampleadjacent to the second sub-block and a second sample adjacent to theleft side (or upper side) of the first sample among the samples of thefirst sub-block. The filtering may represent overlapped motioncompensation filtering. For example, the encoding apparatus may derivesample value 1 of the first sample based on the motion information ofthe first sub-block and derive sample value 2 of the first sample basedon the motion information of the second sub-block. Next, the encodingapparatus may derive a sample value of the first sample based on thesample value 1 and the sample value 2 of the first sample. For example,the encoding apparatus may derive the sample value of the first sampleby weighted sum of the sample value 1 and the sample value 2 of thefirst sample. Further, the sample value of the first sample may bederived based on Equation 1 described above. Further, the encodingapparatus may derive sample value 1 of the first sample based on themotion information of the first sub-block and derive sample value 2 ofthe second sample based on the motion information of the secondsub-block. Next, the encoding apparatus may derive the sample value ofthe second sample based on the sample value 1 and the sample value 2 ofthe second sample. For example, the encoding apparatus may derive thesample value of the second sample by weighted sum of the sample value 1and the sample value 2 of the second sample. Further, the sample valueof the second sample may be derived based on Equation 3 described above.

Further, the encoding apparatus may perform filtering for the firstsample adjacent to the first sub-block among the samples of the secondsub-block. The filtering may represent overlapped motion compensationfiltering. For example, the encoding apparatus may derive sample value 1of the first sample based on the motion information of the firstsub-block and derive sample value 2 of the first sample based on themotion information of the second sub-block. Next, the encoding apparatusmay derive a sample value of the first sample based on the sample value1 and the sample value 2 of the first sample. For example, the encodingapparatus may derive the sample value of the first sample by weightedsum of the sample value 1 and the sample value 2 of the first sample.Further, the sample value of the first sample may be derived based onEquation 1 described above. Alternatively, the sample value of the firstsample may be derived based on Equation 2 described above.

Further, the encoding apparatus may perform filtering for a first sampleadjacent to the first sub-block and a second sample adjacent to theright side (or lower side) of the first sample among the samples of thesecond sub-block. The filtering may represent overlapped motioncompensation filtering. For example, the encoding apparatus may derivesample value 1 of the first sample based on the motion information ofthe first sub-block and derive sample value 2 of the first sample basedon the motion information of the second sub-block. Next, the encodingapparatus may derive a sample value of the first sample based on thesample value 1 and the sample value 2 of the first sample. For example,the encoding apparatus may derive the sample value of the first sampleby weighted sum of the sample value 1 and the sample value 2 of thefirst sample. Further, the sample value of the first sample may bederived based on Equation 1 described above. Further, the encodingapparatus may derive sample value 1 of the first sample based on themotion information of the first sub-block and derive sample value 2 ofthe second sample based on the motion information of the secondsub-block. Next, the encoding apparatus may derive the sample value ofthe second sample based on the sample value 1 and the sample value 2 ofthe second sample. For example, the encoding apparatus may derive thesample value of the second sample by weighted sum of the sample value 1and the sample value 2 of the second sample. Further, the sample valueof the second sample may be derived based on Equation 3 described above.

Meanwhile, the numbers of samples in the first sub-block and the secondsub-block in which the filtering is performed may be determined in unitsof slice or block. Alternatively, the numbers of first sub-blocks andsecond sub-blocks in which the filtering is performed may be determinedbased on the size of the target block. For example, when the size of thetarget block is the 16×16 size, the filtering may be applied to onesample around the split boundary among the samples of the firstsub-block and/or the second sub-block. That is, when the size of thetarget block is the 16×16 size, the filtering may be performed in thefirst sample adjacent to the second sub-block among the samples of thefirst sub-block and the filtering may be performed in the first sampleadjacent to the first sub-block among the samples of the secondsub-block. Further, when the size of the target block is larger than the16×16 size, the filtering may be applied to two samples around the splitboundary among the samples of the first sub-block and/or the secondsub-block. That is, when the size of the target block is larger than the16×16 size, the filtering may be performed for the first sample adjacentto the second sub-block and the second sample adjacent to the left side(or upper side) of the first sample among the samples of the firstsub-block and the filtering may be performed for the first sampleadjacent to the first sub-block and the second sample adjacent to theright side (or lower side) of the first sample among the samples of thesecond sub-block.

Meanwhile, information indicating whether to apply the filtering may begenerated. The information indicating whether to apply the filtering maybe transmitted by the unit such as sequence parameter set (SPS), pictureparameter set (PPS), slice, block, etc., and whether to apply thefiltering to the first sub-block and the second sub-block may bedetermined based on the information indicating whether to apply thefiltering. Alternatively, whether to apply the filtering to the targetblock may be determined based on the information indicating whether toapply the filtering.

Meanwhile, the encoding apparatus may generate a residual signal of thefirst sub-block based on the predicted sample of the first sub-block.The residual signal may be derived as a difference between an originalsample of the first sub-block and the predicted sample. Further, theencoding apparatus may generate the residual signal of the secondsub-block based on the predicted sample of the second sub-block. Theresidual signal may be derived as the difference between the originalsample of the second sub-block and the predicted sample.

The encoding apparatus may generate residual information of the firstsub-block and the second sub-block by performing one transformation forthe residual signal of the first sub-block and the residual signal ofthe second sub-block. For example, the residual signal of the firstsub-block and the residual signal of the second sub-block may becombined into one block and the transformation process for the combinedblock may be performed.

Further, the encoding apparatus may generate residual information of thefirst sub-block and residual information of the second sub-block byperforming separate transformation for the residual signal of the firstsub-block and the residual signal of the second sub-block.

For example, the residual signal of the first sub-block is transformedbased on a transform kernel of a size including the size of the firstsub-block to generate the residual information of the first sub-block.Here, the transform kernel may represent the transform kernel having thesmallest size among transform kernels having sizes including the size ofthe first sub-block.

Alternatively, the residual signal of the first sub-block is transformedto generate the residual information of the first sub-block, but asignal padded with 0 may be combined to the region of the secondsub-block to the residual signal. In this case, the transform may beperformed based on the transform kernel of the size of the target block.

Alternatively, the residual signal of the first sub-block is transformedto generate the residual information of the first sub-block, but theresidual signal may be rearranged to a rectangular block. Meanwhile, theresidual signal may represent residual samples and the residualinformation may represent transform coefficients.

The encoding apparatus encodes and transmits split information andresidual information for the target block (S1430). The encodingapparatus may encode the split information for the target block andoutput the encoded split information in the form of the bitstream. Thesplit information may include information indicating the angle of thesplit boundary and information indicating the distance between the splitboundary and the center of the target block. The target block may besplit into the first sub-block and the second sub-block through thesplit boundary derived based on the information indicating the angle ofthe split boundary and/or the information indicating the distancebetween the split boundary and the center of the target block. Further,the target block may be split along the split boundary which is notvertical to a predetermined boundary and crosses the target block.Alternatively, the additional split information may include a GP splitindex indicating one of a plurality of predetermined split types.

Further, the split information for the target block may include ageometry partition (GP) split flag for the target block and the GP splitflag may indicate whether the target block is split into sub-blockshaving various forms. Alternatively, the GP split flag may indicatewhether the target block is split into sub-blocks through apredetermined split boundary. When the value of the GP split flag is 1,i.e., when the GP split flag indicates that the target block is splitinto the sub-blocks, the target block may be split into a firstsub-block and a second sub-block through a split boundary derived basedon information indicating the angle of the split boundary and/orinformation indicating a distance between the split boundary and thecenter of the target block.

Further, the encoding apparatus may encode the residual information ofthe target information through the bitstream. That is, the encodingapparatus may transmit the residual information of the first sub-blockand the residual information of the first sub-block through thebitstream.

Further, the encoding apparatus may encode the prediction informationfor the first sub-block and output the encoded prediction information inthe form of the bitstream. When the merge mode is applied to the firstsub-block, the prediction information may include a merge index of thefirst sub-block. The merge index may indicate one of the candidates ofthe first motion information candidate list of the first sub-block.Further, when the MVP mode is applied to the first sub-block, theprediction information may include an MVP flag, an MVD, and a referencepicture index of the first sub-block. The MVP flag may indicate one ofthe candidates of the first motion information candidate list and themotion vector of the first sub-block may be derived by adding the motionvector of the candidate derived based on the MVP flag and the MVD. Thereference picture index may indicate a reference picture for predictingthe first sub-block.

Further, the encoding apparatus may encode the information indicatingwhether to apply the filtering through the bitstream. The informationindicating whether to apply the filtering may be transmitted by the unitsuch as sequence parameter set (SPS), picture parameter set (PPS),slice, block, etc., and whether to apply the filtering to the firstsub-block and the second sub-block may be determined based on theinformation indicating whether to apply the filtering. Alternatively,whether to apply the filtering to the target block may be determinedbased on the information indicating whether to apply the filtering.

FIG. 15 schematically illustrates a video decoding method by a decodingapparatus according to the present disclosure. The method disclosed inFIG. 15 may be performed by the decoding apparatus disclosed in FIG. 2.Specifically, for example, S1500 of FIG. 15 may be performed by theentropy decoding unit of the decoding apparatus, S1510 may be performedby the picture partitioner, and S1520 and S1530 may be performed by thepredictor of the decoding apparatus.

The decoding apparatus obtains split information for a target blockthrough a bitstream (S1500). The target block may be a block split in aquad-tree (QT) structure and a block of a terminal node in the QTstructure, which is no longer split in the QT structure. The terminalnode may also be referred to as a leaf node. Here, the QT structure mayrepresent a structure in which a 2N×2N sized target block is split intofour N×N sized sub-blocks. In this case, the target block may be splitin a geometry partition (GP) structure and the split information may berepresented as a GP split structure. The GP structure may represent astructure in which the target block is split into various types ofsub-blocks. Further, the GP structure may represent a structure in whichthe target block is split based on a predetermined split boundary.

The split information may include information indicating the angle ofthe split boundary and information indicating the distance between thesplit boundary and the center of the target block. The target block maybe split into the first sub-block and the second sub-block through thesplit boundary derived based on the information indicating the angle ofthe split boundary and/or the information indicating the distancebetween the split boundary and the center of the target block. Further,the target block may be split along the split boundary which is notvertical to a predetermined boundary and crosses the target block.Alternatively, the additional split information may include a GP splitindex indicating one of a plurality of predetermined split types.

Further, the split information for the target block may include ageometry partition (GP) split flag for the target block and the GP splitflag may indicate whether the target block is split into sub-blockshaving various forms. Alternatively, the GP split flag may indicatewhether the target block is split into sub-blocks through apredetermined split boundary. When the value of the GP split flag is 1,i.e., when the GP split flag indicates that the target block is splitinto the sub-blocks, the target block may be split into a firstsub-block and a second sub-block through a split boundary derived basedon information indicating the angle of the split boundary and/orinformation indicating a distance between the split boundary and thecenter of the target block.

The decoding apparatus splits the target block into a first sub-blockand a second sub-block based on a split boundary indicated by the splitinformation (S1510). The split information may include informationindicating the angle of the split boundary of the target block andinformation indicating the distance between the split boundary and thecenter of the target block and in this case, the target block may besplit into the first sub-block and the second sub-block through thesplit boundary derived based on the information indicating the angle ofthe split boundary and the information indicating the distance betweenthe split boundary and the center of the target block. Alternatively,the split information may include a GP split index indicating one of aplurality of predetermined split types. The split type may indicatewhich boundary of the target block the split boundary crosses. In thiscase, the target block may be split into the first sub-block and thesecond sub-block of the type indicated by the GP split index. The firstsub-block may represent a block positioned at the left side among theblocks split from the target block and the second sub-block mayrepresent a block positioned at the right side among the blocks splitfrom the target block. Further, the first sub-block and the secondsub-block may be non-rectangular blocks.

The decoding apparatus derives a first motion information candidate listfor the first sub-block and a second motion information candidate listfor the second sub-block based on the split type of the target block(S1520). The decoding apparatus may derive the first motion informationcandidate list and the second motion information candidate list based onthe split type derived based on the split information. That is, aspatial neighboring block and/or a temporal neighboring block of thefirst sub-block may be derived according to the split type derived basedon the split information or the spatial neighboring block and/or thetemporal neighboring block of the second sub-block may be derived. Thefirst motion information candidate list may include a spatial candidateindicating motion information of the spatial neighboring block of thefirst sub-block and/or a temporal candidate indicating motioninformation of the temporal neighboring block of the first sub-block inthe co-located picture. That is, the first motion information candidatelist for the first sub-block may be different from the second motioninformation candidate list for the second sub-block. A left height or aright height of the first sub-block may be equal to or smaller than aheight of the target block and an upper width or a lower width of thefirst sub-block may be equal to or smaller than a width of the targetblock. Further, the left height or right height of the second sub-blockmay be equal to or smaller than the height of the target block and theupper width or lower width of the second sub-block may be equal to orsmaller than the width of the target block.

Meanwhile, when a merge mode is applied to the first sub-block, thefirst motion information candidate list may represent a merge candidatelist and when a motion vector prediction (MVP) mode is applied to thefirst sub-block, the first motion information candidate list mayrepresent an MVP candidate list. Further, the second motion informationcandidate list may include a spatial candidate indicating motioninformation of the spatial neighboring block of the second sub-blockand/or a temporal candidate indicating motion information of thetemporal neighboring block of the second sub-block in the co-locatedpicture. Meanwhile, when the merge mode is applied to the secondsub-block, the second motion information candidate list may representthe merge candidate list and when the motion vector prediction (MVP)mode is applied to the second sub-block, the second motion informationcandidate list may represent the MVP candidate list.

Meanwhile, the split types derived based on the split information mayinclude six first to sixth types.

For example, the first type may represent a type in which the firstsub-block has the triangular shape and is split to include the top-leftsample of the target block. Further, the first type may represent a typein which the split boundary crosses the upper boundary and the leftboundary of the target block.

When the target block is split into the first type, i.e., the splitboundary crosses the upper boundary and the left boundary of the targetblock, the upper width of the first sub-block is UW, the left height ofthe first sub-block is LH, and an x component of the top-left sampleposition of the first sub-block is 0 and a y component is 0, the firstmotion information candidate list may include a first spatial candidateindicating motion information of a first spatial neighboring block, asecond spatial candidate indicating motion information of a secondspatial neighboring block, a third spatial candidate indicating motioninformation of a third spatial neighboring block, and/or a fourthspatial candidate indicating motion information of a fourth spatialneighboring block. In this case, a location of the first spatialneighboring block may be (−1, LH), the location of the second spatialneighboring block may be (−1, LH−1), the location of the third spatialneighboring block may be (UW, −1), and the location of the fourthspatial neighboring block may be (UW−1, −1). Further, the first motioninformation candidate list may include a temporal candidate indicatingmotion information of the temporal neighboring block in the co-locatedpicture. In this case, the location of the temporal neighboring blockmay be (0, LH−1).

Further, when the target block is split into the first type, i.e., thesplit boundary crosses the upper boundary and the left boundary of thetarget block, the upper width of the first sub-block is UW, the leftheight of the first sub-block is LH, and an x component of the top-leftsample position of the target block is 0 and a y component is 0, thefirst motion information candidate list may include a first spatialcandidate indicating motion information of a first spatial neighboringblock, a second spatial candidate indicating motion information of asecond spatial neighboring block, a third spatial candidate indicatingmotion information of a third spatial neighboring block, and/or a fourthspatial candidate indicating motion information of a fourth spatialneighboring block. In this case, a location of the first spatialneighboring block may be (−1, LH), the location of the second spatialneighboring block may be (−1, LH−1), the location of the third spatialneighboring block may be (UW, −1), and the location of the fourthspatial neighboring block may be (UW−1, −1). Further, the first motioninformation candidate list may include a temporal candidate indicatingmotion information of the temporal neighboring block in the co-locatedpicture. In this case, the location of the temporal neighboring blockmay be (0, LH−1).

Further, when the target block is split into the first type, i.e., thesplit boundary crosses the upper boundary and the left boundary of thetarget block, the upper width of the second sub-block is UW, and the xcomponent of the top-left sample position of the second sub-block is 0and the y component is 0, the second motion information candidate listmay include the spatial candidate indicating the motion information ofthe spatial neighboring block. In this case, the location of the spatialneighboring block may be (−1, −1).

Further, when the target block is split into the first type, i.e., thesplit boundary crosses the upper boundary and the left boundary of thetarget block, the upper width of the second sub-block is UW, the size ofthe target block is N×N, and the x component of the top-left sampleposition of the target block is 0 and the y component is 0, the secondmotion information candidate list may include the spatial candidateindicating the motion information of the spatial neighboring block. Inthis case, the location of the spatial neighboring block may be (N−UW−1,−1).

As another example, the second type may represent a type in which thesecond sub-block has the triangular shape and is split to include thebottom-right sample of the target block. Further, the second type mayrepresent a type in which the split boundary crosses the right boundaryand the lower boundary of the target block.

When the target block is split into the second type, i.e., the splitboundary crosses the right boundary and the lower boundary of the targetblock, the lower width of the second sub-block is DW, the right heightof the second sub-block is RH, and the x component of the top-leftsample position of the second sub-block is 0 and the y component is 0,the second motion information candidate list may include a first spatialcandidate indicating motion information of a first spatial neighboringblock, a second spatial candidate indicating motion information of asecond spatial neighboring block, a third spatial candidate indicatingmotion information of a third spatial neighboring block, and/or a fourthspatial candidate indicating motion information of a fourth spatialneighboring block. In this case, the location of the first spatialneighboring block may be (−DW, RH), the location of the second spatialneighboring block may be (−DW, RH−1), the location of the third spatialneighboring block may be (−1, −1), and the location of the fourthspatial neighboring block may be (0, −1). Further, the first motioninformation candidate list may include a temporal candidate indicatingmotion information of the temporal neighboring block in the co-locatedpicture. In this case, the location of the temporal neighboring blockmay be (0, LH).

Further, when the target block is split into the second type, i.e., thesplit boundary crosses the right boundary and the lower boundary of thetarget block, the lower width of the second sub-block is DW, the rightheight of the second sub-block is RH, the size of the target block isN×N, and the x component of the top-left sample position of the targetblock is 0 and the y component is 0, the second motion informationcandidate list may include a first spatial candidate indicating motioninformation of a first spatial neighboring block, a second spatialcandidate indicating motion information of a second spatial neighboringblock, a third spatial candidate indicating motion information of athird spatial neighboring block, and/or a fourth spatial candidateindicating motion information of a fourth spatial neighboring block. Inthis case, the location of the first spatial neighboring block may be(N−1−DW, N), the location of the second spatial neighboring block may be(N−1−DW, N−1), the location of the third spatial neighboring block maybe (N, N−1−RH), and the location of the fourth spatial neighboring blockmay be (N−1, N−1−RH). Further, the second motion information candidatelist may include a temporal candidate indicating motion information ofthe temporal neighboring block in the co-located picture. In this case,the location of the temporal neighboring block may be (N, N).

Further, when the target block is split into the second type, i.e., thesplit boundary crosses the right boundary and the lower boundary of thetarget block, the left height of the first sub-block is LH, the lowerwidth of the first sub-block is DW, and the x component of the top-leftsample position of the first sub-block is 0 and the y component is 0,the first motion information candidate list may include the temporalcandidate indicating the motion information of the temporal neighboringblock in the co-located picture. In this case, the location of thetemporal neighboring block may be (DW−1, LH−1).

Further, when the target block is split into the second type, i.e., thesplit boundary crosses the right boundary and the lower boundary of thetarget block, the left height of the first sub-block is LH, the lowerwidth of the first sub-block is DW, and the x component of the top-leftsample position of the target block is 0 and the y component is 0, thefirst motion information candidate list may include the temporalcandidate indicating the motion information of the temporal neighboringblock in the co-located picture. In this case, the location of thetemporal neighboring block may be (DW−1, LH−1).

As another example, the third type may represent a type in which thesecond sub-block has the triangular shape and is split to include thetop-right sample of the target block. Further, the third type mayrepresent a type in which the split boundary crosses the upper boundaryand the right boundary of the target block.

Further, when the target block is split into the third type, i.e., thesplit boundary crosses the upper boundary and the right boundary of thetarget block, the upper width of the first sub-block is UW, and the xcomponent of the top-left sample position of the first sub-block is 0and the y component is 0, the first motion information candidate listmay include a first spatial candidate indicating the motion informationof the first spatial neighboring block and a second spatial candidateindicating the motion information of the second spatial neighboringblock. In this case, the location of the first spatial neighboring blockmay be (UW, −1) and the location of the second spatial neighboring blockmay be (UW−1, −1).

Further, when the target block is split into the third type, i.e., thesplit boundary crosses the upper boundary and the right boundary of thetarget block, the upper width of the first sub-block is UW, and the xcomponent of the top-left sample position of the target block is 0 andthe y component is 0, the first motion information candidate list mayinclude a first spatial candidate indicating the motion information ofthe first spatial neighboring block and a second spatial candidateindicating the motion information of the second spatial neighboringblock. In this case, the location of the first spatial neighboring blockmay be (UW, −1) and the location of the second spatial neighboring blockmay be (UW−1, −1).

Further, when the target block is split into the third type, i.e., thesplit boundary crosses the upper boundary and the right boundary of thetarget block, and the x component of the top-left sample position of thesecond sub-block is 0 and the y component is 0, the second motioninformation candidate list may include the spatial candidate indicatingthe motion information of the spatial neighboring block. In this case,the location of the spatial neighboring block may be (−1, −1). Further,the second motion information candidate list may include a temporalcandidate indicating motion information of the temporal neighboringblock in the co-located picture. For example, when the target block issplit into the third type, i.e., the split boundary crosses the upperboundary and the right boundary of the target block, the upper width ofthe second sub-block is UW, the right height of the second sub-block isRH, the size of the target block is N×N, and the x component of thetop-left sample position of the second sub-block is 0 and the ycomponent is 0, the location of the temporal neighboring block may be(UW, N). Meanwhile, the location of the temporal neighboring block maybe (UW−1, RH−1).

Further, when the target block is split into the third type, i.e., thesplit boundary crosses the upper boundary and the right boundary of thetarget block, the upper width of the second sub-block is UW, the size ofthe target block is N×N, and the x component of the top-left sampleposition of the target block is 0 and the y component is 0, the secondmotion information candidate list may include the spatial candidateindicating the motion information of the spatial neighboring block. Inthis case, the location of the spatial neighboring block may be (N−1−UW,−1). Further, the second motion information candidate list may include atemporal candidate indicating motion information of the temporalneighboring block in the co-located picture. For example, when thetarget block is split into the third type, i.e., the split boundarycrosses the upper boundary and the right boundary of the target block,the right height of the second sub-block is RH, the size of the targetblock is N×N, and the x component of the top-left sample position of thetarget block is 0 and the y component is 0, the location of the temporalneighboring block may be (N, N). Meanwhile, the location of the temporalneighboring block may be (N−1, RH−1).

As another example, a fourth type may represent a type in which thefirst sub-block has the triangular shape and is split to include thebottom-left sample of the target block. Further, the fourth type mayrepresent a type in which the split boundary crosses the left boundaryand the lower boundary of the target block.

Further, when the target block is split into the fourth type, i.e., thesplit boundary crosses the left boundary and the lower boundary of thetarget block, the upper width of the second sub-block is UW, the lowerwidth of the second sub-block is DW, the right height of the secondsub-block is RH, and the x component of the top-left sample position ofthe second sub-block is 0 and the y component is 0, the second motioninformation candidate list may include a first spatial candidateindicating the motion information of the first spatial neighboring blockand a second spatial candidate indicating the motion information of thesecond spatial neighboring block. In this case, the location of thefirst spatial neighboring block may be (UW−1−DW, RH) and the location ofthe second spatial neighboring block may be (UW−1−DW, RH−1).

Further, when the target block is split into the fourth type, i.e., thesplit boundary crosses the left boundary and the lower boundary of thetarget block, the lower width of the second sub-block is DW, the size ofthe target block is N×N, and the x component of the top-left sampleposition of the target block is 0 and the y component is 0, the secondmotion information candidate list may include a first spatial candidateindicating the motion information of the first spatial neighboring blockand a second spatial candidate indicating the motion information of thesecond spatial neighboring block. In this case, the location of thefirst spatial neighboring block may be (N−1−DW, N) and the location ofthe second spatial neighboring block may be (N−1−DW, N−1).

Further, when the target block is split into the fourth type, i.e., thesplit boundary crosses the left boundary and the lower boundary of thetarget block, the left height of the first sub-block is LH, the lowerwidth of the first sub-block is DW, and the x component of the top-leftsample position of the first sub-block is 0 and the y component is 0,the first motion information candidate list may include the temporalcandidate indicating the motion information of the temporal neighboringblock in the co-located picture. In this case, the location of thetemporal neighboring block may be (DW−1, LH−1).

Further, when the target block is split into the fourth type, i.e., thesplit boundary crosses the left boundary and the lower boundary of thetarget block, the lower width of the first sub-block is DW, the size ofthe target block is N×N, and the x component of the top-left sampleposition of the target block is 0 and the y component is 0, the firstmotion information candidate list may include the temporal candidateindicating the motion information of the temporal neighboring block inthe co-located picture. In this case, the location of the temporalneighboring block may be (DW−1, N−1).

As another example, a fifth type may represent a type in which the firstsub-block and the second sub-block have a rectangular shape and the leftboundary of the first sub-block and the right height of the secondsub-block are split to be the same as the height of the target block.Further, the fifth type may represent a type in which the split boundarycrosses the upper boundary and the lower boundary of the target block.

When the target block is split into the fifth type, i.e., the splitboundary crosses the upper boundary and the lower boundary of the targetblock, the upper width of the first sub-block is UW, and the x componentof the top-left sample position of the first sub-block is 0 and the ycomponent is 0, the first motion information candidate list may includea first spatial candidate indicating the motion information of the firstspatial neighboring block and a second spatial candidate indicating themotion information of the second spatial neighboring block. In thiscase, the location of the first spatial neighboring block may be (UW,−1) and the location of the second spatial neighboring block may be(UW−1, −1). Further, the first motion information candidate list mayinclude a temporal candidate indicating motion information of thetemporal neighboring block in the co-located picture. For example, whenthe target block is split into the fifth type, i.e., the split boundarycrosses the upper boundary and the lower boundary of the target block,the left height of the first sub-block is LH, the lower width of thefirst sub-block is DW, and the x component of the top-left sampleposition of the first sub-block is 0 and the y component is 0, thelocation of the temporal neighboring block may be (DW−1, LH−1).

Further, when the target block is split into the fifth type, i.e., thesplit boundary crosses the upper boundary and the lower boundary of thetarget block, the upper width of the first sub-block is UW, the lowerwidth of the first sub-block is DW, the size of the target block is N×N,and the x component of the top-left sample position of the target blockis 0 and the y component is 0, the first motion information candidatelist may include at least one of a first spatial candidate indicatingthe motion information of the first spatial neighboring block and asecond spatial candidate indicating the motion information of the secondspatial neighboring block, and a temporal candidate indicating themotion information of the temporal neighboring block in the co-locatedpicture. In this case, the location of the first spatial neighboringblock may be (UW, −1) and the location of the second spatial neighboringblock may be (UW−1, −1), and the location of the temporal neighboringblock may be (DW−1, N−1).

Further, when the target block is split into the fifth type, i.e., thesplit boundary crosses the upper boundary and the lower boundary of thetarget block, the upper width of the second sub-block is UW, the lowerwidth of the second sub-block is DW, the right height of the secondsub-block is RH, and the x component of the top-left sample position ofthe second sub-block is 0 and the y component is 0, the second motioninformation candidate list may include at least one of a first spatialcandidate indicating the motion information of the first spatialneighboring block, a second spatial candidate indicating the motioninformation of the second spatial neighboring block, and a third spatialcandidate indicating the motion information of the third spatialneighboring block, and a temporal candidate indicating the motioninformation of the temporal neighboring block in the co-located picture.In this case, the location of the first spatial neighboring block may be(UW−1−DW, RH), the location of the second spatial neighboring block maybe (UW−1−DW, RH−1), the location of the third spatial neighboring blockmay be (−1, −1), and the location of the temporal neighboring block maybe (UW−1, RH−1).

Further, when the target block is split into the fifth type, i.e., thesplit boundary crosses the upper boundary and the lower boundary of thetarget block, the upper width of the second sub-block is UW, the lowerwidth of the first sub-block is DW, the size of the target block is N×N,and the x component of the top-left sample position of the target blockis 0 and the y component is 0, the second motion information candidatelist may include at least one of a first spatial candidate indicatingthe motion information of the first spatial neighboring block, a secondspatial candidate indicating the motion information of the secondspatial neighboring block, and a third spatial candidate indicating themotion information of the third spatial neighboring block, and atemporal candidate indicating the motion information of the temporalneighboring block in the co-located picture. In this case, the locationof the first spatial neighboring block may be (N−1−DW, N), the locationof the second spatial neighboring block may be (N−1−DW, N−1), thelocation of the third spatial neighboring block may be (N−1−UW, −1), andthe location of the temporal neighboring block may be (N, N).

As another example, a sixth type may represent a type in which the firstsub-block and the second sub-block have a rectangular shape and theupper boundary of the first sub-block and the lower width of the secondsub-block are split to be the same as the height of the target block.Further, the sixth type may represent a type in which the split boundarycrosses the left boundary and the right boundary of the target block.

Further, when the target block is split into the sixth type, i.e., thesplit boundary crosses the left boundary and the right boundary of thetarget block, the left height of the first sub-block is LH, and the xcomponent of the top-left sample position of the first sub-block is 0and the y component is 0, the first motion information candidate listmay include a first spatial candidate indicating the motion informationof the first spatial neighboring block and a second spatial candidateindicating the motion information of the second spatial neighboringblock. In this case, the location of the first spatial neighboring blockmay be (−1, LH) and the location of the second spatial neighboring blockmay be (−1, LH−1). Further, the first motion information candidate listmay include a temporal candidate indicating motion information of thetemporal neighboring block in the co-located picture. For example, whenthe target block is split into the sixth type, i.e., the split boundarycrosses the left boundary and the right boundary of the target block,the left height of the first sub-block is LH, and the x component of thetop-left sample position of the first sub-block is 0 and the y componentis 0, the location of the temporal neighboring block may be (0, LH−1).

Further, when the target block is split into the sixth type, i.e., thesplit boundary crosses the left boundary and the right boundary of thetarget block, the left height of the first sub-block is LH, and the xcomponent of the top-left sample position of the target block is 0 andthe y component is 0, the first motion information candidate list mayinclude a first spatial candidate indicating the motion information ofthe first spatial neighboring block and a second spatial candidateindicating the motion information of the second spatial neighboringblock. In this case, the location of the first spatial neighboring blockmay be (−1, LH) and the location of the second spatial neighboring blockmay be (−1, LH−1). Further, the first motion information candidate listmay include a temporal candidate indicating motion information of thetemporal neighboring block in the co-located picture. For example, whenthe target block is split into the sixth type, i.e., the split boundarycrosses the left boundary and the right boundary of the target block,the left height of the first sub-block is LH, and the x component of thetop-left sample position of the target block is 0 and the y component is0, the location of the temporal neighboring block may be (0, LH−1).

Further, when the target block is split into the sixth type, i.e., thesplit boundary crosses the left boundary and the right boundary of thetarget block, the lower width of the second sub-block is DW, the leftheight of the second sub-block is LH, the right height of the secondsub-block is RH, and the x component of the top-left sample position ofthe second sub-block is 0 and the y component is 0, the second motioninformation candidate list may include a first spatial candidateindicating the motion information of the first spatial neighboring blockand a second spatial candidate indicating the motion information of thesecond spatial neighboring block. In this case, the location of thefirst spatial neighboring block may be (DW, LH−1−RH) and the location ofthe second spatial neighboring block may be (DW−1, LH−1−RH).

Further, when the target block is split into the sixth type, i.e., thesplit boundary crosses the left boundary and the right boundary of thetarget block, the right height of the second sub-block is RH, the sizeof the target block is N×N, and the x component of the top-left sampleposition of the target block is 0 and the y component is 0, the secondmotion information candidate list may include a first spatial candidateindicating the motion information of the first spatial neighboring blockand a second spatial candidate indicating the motion information of thesecond spatial neighboring block. In this case, the location of thefirst spatial neighboring block may be (N, N−1−RH) and the location ofthe second spatial neighboring block may be (N−1, N−1−RH).

The decoding apparatus performs inter prediction of the first sub-blockbased on the first motion information candidate list and performs interprediction of the second sub-block based on the second motioninformation candidate list (S1530). The decoding apparatus mayseparately perform the prediction for each of the first sub-block andthe second sub-block.

The decoding apparatus may perform inter prediction of the firstsub-block based on the first motion information candidate list.Specifically, the decoding apparatus may perform the motion informationof the first sub-block based on the first motion information candidatelist. For example, when the merge mode is applied to the firstsub-block, the first motion information candidate list may represent amerge candidate list and the motion information of the candidateselected based on the merge index in the first motion informationcandidate list may be derived as the motion information of the firstsub-block. Prediction information of the first sub-block may be obtainedthrough the bitstream and the prediction information may include themerge index. The motion information of the first sub-block may include areference picture index and a motion vector.

The decoding apparatus may perform the inter prediction for the firstsub-block based on the motion information. Specifically, the decodingapparatus may derive a reference block of the first sub-block based onthe motion information. That is, the decoding apparatus may derive areference block indicating the motion vector in the reference pictureindicated by the reference picture index. The decoding apparatus maypredict the first sub-block based on the reference block. That is, thedecoding apparatus may derive a reconstructed sample in the referenceblock as a predicted sample of the first sub-block.

Further, for example, when the motion vector prediction (MVP) mode isapplied to the first sub-block, the first motion information candidatelist may represent an MVP candidate list and a motion vector of thecandidate selected based on the MVP flag in the first motion informationcandidate list may be derived as a motion vector predictor (MVP) of thefirst sub-block. The prediction information for the first sub-block maybe obtained through the bitstream and the prediction information mainclude the MVP flag, and the reference picture index and the motionvector difference (MVD) of the first sub-block. In this case, thedecoding apparatus may derive the motion vector of the first sub-blockby adding the MVP and the MVD.

The decoding apparatus may perform the inter prediction for the firstsub-block based on the motion information. Specifically, the decodingapparatus may derive the reference block of the first sub-block based onthe motion vector and the reference picture index. That is, the decodingapparatus may derive a reference block indicating the motion vector inthe reference picture indicated by the reference picture index. Thedecoding apparatus may predict the first sub-block based on thereference block. That is, the decoding apparatus may derive areconstructed sample in the reference block as a predicted sample of thefirst sub-block.

Further, the decoding apparatus may perform inter prediction of thesecond sub-block based on the second motion information candidate list.The decoding apparatus may perform the motion information of the secondsub-block based on the second motion information candidate list. Forexample, when the merge mode is applied to the second sub-block, thesecond motion information candidate list may represent the mergecandidate list and the motion information of the candidate selectedbased on the merge index in the second motion information candidate listmay be derived as the motion information of the second sub-block.Prediction information of the second sub-block may be obtained throughthe bitstream and the prediction information may include the mergeindex. The motion information of the second sub-block may include thereference picture index and the motion vector.

The decoding apparatus may perform the inter prediction for the secondsub-block based on the motion information. Specifically, the decodingapparatus may derive the reference block of the second sub-block basedon the motion information. That is, the decoding apparatus may derive areference block indicating the motion vector in the reference pictureindicated by the reference picture index. The decoding apparatus maypredict the second sub-block based on the reference block. That is, thedecoding apparatus may derive the reconstructed sample in the referenceblock as the predicted sample of the second sub-block.

Further, for example, when the motion vector prediction (MVP) mode isapplied to the second sub-block, the second motion information candidatelist may represent the MVP candidate list and the motion vector of thecandidate selected based on the MVP flag in the second motioninformation candidate list may be derived as the motion vector predictor(MVP) of the second sub-block. The prediction information for the secondsub-block may be obtained through the bitstream and the predictioninformation may include the MVP flag, and the reference picture indexand the motion vector difference (MVD) of the second sub-block. In thiscase, the decoding apparatus may derive the motion vector of the secondsub-block by adding the MVP and the MVD.

The decoding apparatus may perform the inter prediction for the secondsub-block based on the motion information. Specifically, the decodingapparatus may derive the reference block of the second sub-block basedon the motion vector and the reference picture index. That is, thedecoding apparatus may derive a reference block indicating the motionvector in the reference picture indicated by the reference pictureindex. The decoding apparatus may predict the second sub-block based onthe reference block. That is, the decoding apparatus may derive thereconstructed sample in the reference block as the predicted sample ofthe second sub-block.

Further, the decoding apparatus may perform filtering for a first sampleadjacent to the second sub-block among the samples of the firstsub-block. The filtering may represent overlapped motion compensationfiltering. For example, the decoding apparatus may derive sample value 1of the first sample based on the motion information of the firstsub-block and derive sample value 2 of the first sample based on themotion information of the second sub-block. Next, the decoding apparatusmay derive a sample value of the first sample based on the sample value1 and the sample value 2 of the first sample. For example, the decodingapparatus may derive the sample value of the first sample by weightedsum of the sample value 1 and the sample value 2 of the first sample.Further, the sample value of the first sample may be derived based onEquation 1 described above. Alternatively, the sample value of the firstsample may be derived based on Equation 2 described above.

Further, the decoding apparatus may perform filtering for a first sampleadjacent to the second sub-block and a second sample adjacent to theleft side (or upper side) of the first sample among the samples of thefirst sub-block. The filtering may represent overlapped motioncompensation filtering. For example, the decoding apparatus may derivesample value 1 of the first sample based on the motion information ofthe first sub-block and derive sample value 2 of the first sample basedon the motion information of the second sub-block. Next, the decodingapparatus may derive a sample value of the first sample based on thesample value 1 and the sample value 2 of the first sample. For example,the decoding apparatus may derive the sample value of the first sampleby weighted sum of the sample value 1 and the sample value 2 of thefirst sample. Further, the sample value of the first sample may bederived based on Equation 1 described above. Further, the decodingapparatus may derive sample value 1 of the first sample based on themotion information of the first sub-block and derive sample value 2 ofthe second sample based on the motion information of the secondsub-block. Next, the decoding apparatus may derive a sample value of thefirst sample based on the sample value 2 and the sample value 2 of thesecond sample. For example, the decoding apparatus may derive the samplevalue of the first sample by weighted sum of the sample value 2 and thesample value 2 of the second sample. Further, the sample value of thesecond sample may be derived based on Equation 3 described above.

Further, the decoding apparatus may perform filtering for a first sampleadjacent to the first sub-block among the samples of the secondsub-block. The filtering may represent overlapped motion compensationfiltering. For example, the decoding apparatus may derive sample value 1of the first sample based on the motion information of the firstsub-block and derive sample value 2 of the first sample based on themotion information of the second sub-block. Next, the decoding apparatusmay derive a sample value of the first sample based on the sample value1 and the sample value 2 of the second sample. For example, the decodingapparatus may derive the sample value of the first sample by weightedsum of the sample value 1 and the sample value 2 of the second sample.Further, the sample value of the first sample may be derived based onEquation 1 described above. Alternatively, the sample value of the firstsample may be derived based on Equation 2 described above.

Further, the decoding apparatus may perform filtering for a first sampleadjacent to the first sub-block and a second sample adjacent to theright side (or lower side) of the first sample among the samples of thesecond sub-block. The filtering may represent overlapped motioncompensation filtering. For example, the decoding apparatus may derivesample value 1 of the first sample based on the motion information ofthe first sub-block and derive sample value 2 of the first sample basedon the motion information of the second sub-block. Next, the decodingapparatus may derive a sample value of the first sample based on thesample value 1 and the sample value 2 of the second sample. For example,the decoding apparatus may derive the sample value of the first sampleby weighted sum of the sample value 1 and the sample value 2 of thesecond sample. Further, the sample value of the first sample may bederived based on Equation 1 described above. Further, the decodingapparatus may derive sample value 1 of the first sample based on themotion information of the first sub-block and derive sample value 2 ofthe second sample based on the motion information of the secondsub-block. Next, the decoding apparatus may derive a sample value of thefirst sample based on the sample value 2 and the sample value 2 of thesecond sample. For example, the decoding apparatus may derive the samplevalue of the first sample by weighted sum of the sample value 2 and thesample value 2 of the second sample. Further, the sample value of thesecond sample may be derived based on Equation 3 described above.

Meanwhile, the numbers of samples in the first sub-block and the secondsub-block in which the filtering is performed may be determined in unitsof slice or block. Alternatively, the numbers of first sub-blocks andsecond sub-blocks in which the filtering is performed may be determinedbased on the size of the target block. For example, when the size of thetarget block is the 16×16 size, the filtering may be applied to onesample around the split boundary among the samples of the firstsub-block and the second sub-block. That is, when the size of the targetblock is the 16×16 size, the filtering may be performed in the firstsample adjacent to the second sub-block among the samples of the firstsub-block and the filtering may be performed in the first sampleadjacent to the first sub-block among the samples of the secondsub-block. Further, when the size of the target block is larger than the16×16 size, the filtering may be applied to two samples around the splitboundary among the samples of the first sub-block and/or the secondsub-block. That is, when the size of the target block is larger than the16×16 size, the filtering may be performed for the first sample adjacentto the second sub-block and the second sample adjacent to the left side(or upper side) of the first sample among the samples of the firstsub-block and the filtering may be performed for the first sampleadjacent to the first sub-block and the second sample adjacent to theright side (or lower side) of the first sample among the samples of thesecond sub-block.

Meanwhile, the information indicating whether to apply the filtering maybe transmitted by the unit such as sequence parameter set (SPS), pictureparameter set (PPS), slice, block, etc., and whether to apply thefiltering to the first sub-block and the second sub-block may bedetermined based on the information indicating whether to apply thefiltering. Alternatively, whether to apply the filtering to the targetblock may be determined based on the information indicating whether toapply the filtering.

Meanwhile, the decoding apparatus may obtain residual information of thefirst sub-block and the second sub-block through the bitstream. In thiscase, the decoding apparatus may generate the residual signals of thefirst sub-block and the second sub-block by performing onetransformation for the residual information of the first sub-block andthe second sub-block. Here, the residual information may indicatetransform coefficients. Further, the residual signal may representresidual samples.

Meanwhile, the decoding apparatus may obtain the residual information ofthe first sub-block and/or the residual information of the secondsub-block through the bitstream. Further, the decoding apparatus maygenerate the residual signal of the first sub-block and the residualsignal of the second sub-block by performing separate transformation forthe residual information of the first sub-block and the residualinformation of the second sub-block.

For example, the residual information of the first sub-block istransformed based on a transform kernel of a size including the size ofthe first sub-block to generate the residual signal of the firstsub-block. Here, the transform kernel may represent the transform kernelhaving the smallest size among transform kernels having sizes includingthe size of the first sub-block.

Alternatively, the residual information of the first sub-block istransformed to generate the residual signal of the first sub-block, butthe residual signal may include a signal padded to 0 for the region ofthe second sub-block. In this case, the transform may be performed basedon the transform kernel of the size of the target block.

Alternatively, the residual information of the first sub-block istransformed to generate the residual signal of the first sub-block, butthe residual signal may include a residual signal included in arearranged first sub-block. The rearranged first sub-block may be ablock in which the first sub-block is rearranged in a rectangular shape.

The decoding apparatus may generate the reconstructed sample by addingthe predicted sample of the first sub-block and the residual signal andgenerate the reconstructed picture based on the reconstructed sample.Further, the decoding apparatus may generate the reconstructed sample byadding the predicted sample of the second sub-block and the residualsignal and generate the reconstructed picture based on the reconstructedsample. Thereafter, the decoding apparatus may apply an in-loopfiltering procedure such as a deblocking filtering and/or SAO procedureto the reconstructed picture in order to enhance subjective/objectivepicture quality as necessary.

According to the present disclosure, according to split types of blockssplit through a GP structure, spatial motion information candidates ofthe blocks can be derived, thereby enhancing prediction efficiency andenhancing overall coding efficiency.

Further, according to the present disclosure, according to the splittypes of blocks split through the GP structure, temporal motioninformation candidates of the blocks can be derived, thereby enhancingthe prediction efficiency and enhancing the overall coding efficiency.

Further, according to the present disclosure, filtering samples around aboundary of the blocks split through the GP structure, thereby enhancingprediction accuracy and enhancing the overall coding efficiency.

In addition, according to the present disclosure, a transform process ofthe blocks split through the GP structure can be performed, therebyenhancing transform efficiency and enhancing the overall codingefficiency.

In the aforementioned embodiment, the methods are described based on theflowcharts as a series of steps or blocks, but the present disclosure isnot limited to the order of steps, and a certain step may occur indifferent order from or simultaneously with a step different from thatdescribed above. Further, those skilled in the art will understand thatthe steps shown in the flowchart are not exclusive and other steps maybe included or one or more steps in the flowcharts may be deletedwithout affecting the scope of the present disclosure.

The aforementioned method according to the present disclosure may beimplemented in the form of software, and the encoding apparatus and/orthe decoding apparatus according to the present disclosure may beincluded in the apparatus for performing image processing of, forexample, a TV, a computer, a smartphone, a set-top box, a displaydevice, and the like.

When the embodiments in the present disclosure are implemented insoftware, the aforementioned method may be implemented as a module(process, function, and the like) for performing the aforementionedfunction. The module may be stored in a memory and executed by aprocessor. The memory may be located inside or outside the processor,and may be coupled with the processor by various well-known means. Theprocessor may include application-specific integrated circuits (ASICs),other chipsets, logic circuits, and/or data processing devices. Thememory may include a read-only memory (ROM), a random access memory(RAM), a flash memory, a memory card, a storage medium and/or otherstorage devices.

What is claimed is:
 1. A video decoding method performed by a decodingapparatus, comprising: obtaining residual information and splitinformation for a target block from a bitstream; splitting the targetblock into a first sub-partition and a second sub-partition based on asplit boundary indicated by the split information; deriving a firstmotion information candidate list for the first sub-partition and asecond motion information candidate list for the second sub-partition;deriving prediction samples in the first sub-partition based on thefirst motion information candidate list; deriving prediction samples inthe second sub-partition based on the second motion informationcandidate list; deriving residual samples of the target block based onthe residual information; and generating a reconstructed picture basedon the prediction samples in the first sub-partition, the predictionsamples in the second sub-partition and the residual samples, whereinthe first sub-partition and the second sub-partition are non-rectangularpartitions, wherein the split information includes information on anangle of the split boundary and a distance between the split boundaryand a center of the target block, wherein the target block is split intothe first sub-partition and the second sub-partition through the splitboundary derived based on the information on the angle of the splitboundary and the distance between the split boundary and the center ofthe target block, and wherein based on a right height of the secondsub-partition being RH, a size of the target block being N×N, and an xcomponent of a top-left sample position of the target block being 0 anda y component of the top-left sample position being 0, the second motioninformation candidate list includes at least one of a first spatialcandidate indicating motion information of a first spatial neighboringblock and a second spatial candidate indicating motion information of asecond spatial neighboring block, a location of the first spatialneighboring block is (N, N−1−RH), and a location of the second spatialneighboring block is (N−1, N−1−RH).
 2. The video decoding method ofclaim 1, wherein based on the split boundary crossing an upper boundaryand a left boundary of the target block, an upper width of the firstsub-partition being UW, a left height of the first sub-partition beingLH, and an x component of a top-left sample position of the target blockbeing 0 and a y component of the top-left sample position being 0, thefirst motion information candidate list includes at least one of a firstspatial candidate indicating motion information of a first spatialneighboring block, a second spatial candidate indicating motioninformation of a second spatial neighboring block, a third spatialcandidate indicating motion information of a third spatial neighboringblock, a fourth spatial candidate indicating motion information of afourth spatial neighboring block, and a temporal candidate indicatingmotion information of a temporal neighboring block in a co-locatedpicture, a location of the first spatial neighboring block is (−1, LH),a location of the second spatial neighboring block is (−1, LH−1), alocation of the third spatial neighboring block is (UW, −1), a locationof the fourth spatial neighboring block is (UW−1, −1), and a location ofthe temporal neighboring block may be (0, LH−1).
 3. The video decodingmethod of claim 1, wherein based on the split boundary crossing a rightboundary and a lower boundary of the target block, a lower width of thefirst sub-partition being DW, a left height of the first sub-partitionbeing LH, and an x component of a top-left sample position of the targetblock being 0 and a y component of the top-left sample position being 0,and a location of a temporal neighboring block is (DW−1, LH−1).
 4. Thevideo decoding method of claim 1, wherein based on the split boundarycrossing a right boundary and a lower boundary of the target block, alower width of the second sub-partition being DW, a right height of thesecond sub-partition being RH, a size of the target block being N x N,and an x component of a top-left sample position of the target blockbeing 0 and a y component of the top-left sample position being 0, thesecond motion information candidate list includes at least one of athird spatial candidate indicating motion information of a third spatialneighboring block and a fourth spatial candidate indicating motioninformation of a fourth spatial neighboring block, a location of thethird spatial neighboring block is (N−1−DW, N), and a location of thefourth spatial neighboring block is (N−1−DW, N−1).
 5. The video decodingmethod of claim 1, wherein based on the split boundary crossing an upperboundary and a right boundary of the target block, an upper width of thefirst sub-partition being UW, and an x component of a top-left sampleposition of the target block being 0 and a y component of the top-leftsample position being 0, the first motion information candidate listincludes at least one of a first spatial candidate indicating motioninformation of a first spatial neighboring block and a second spatialcandidate indicating motion information of a second spatial neighboringblock, a location of the first spatial neighboring block is (UW, −1),and a location of the second spatial neighboring block is (UW−1, −1). 6.The video decoding method of claim 1, wherein based on the splitboundary crossing an upper boundary and a right boundary of the targetblock, an upper width of the second sub-partition being UW, a size ofthe target block being N×N, and an x component of a top-left sampleposition of the target block being 0 and a y component of the top-leftsample position being 0, the second motion information candidate listincludes a temporal candidate indicating motion information of atemporal neighboring block in a co-located picture, a location of thetemporal neighboring block is (N, N).
 7. The video decoding method ofclaim 1, wherein based on the split boundary crossing a left boundaryand a lower boundary of the target block, a left height of the firstsub-partition being LH, a lower width of the first sub-partition beingDW, a size of the target block being N×N, and an x component of atop-left sample position of the target block being 0 and a y componentof the top-left sample position being 0, the first motion informationcandidate list includes a temporal candidate indicating motioninformation of a temporal neighboring block in a co-located picture, anda location of the temporal neighboring block is (DW−1, N−1).
 8. Thevideo decoding method of claim 1, wherein based on the split boundarycrossing an upper boundary and a lower boundary of the target block, anupper width of the first sub-partition being UW, a lower width of thefirst sub-partition being DW, a size of the target block being N x N,and an x component of a top-left sample position of the target blockbeing 0 and a y component of the top-left sample position being 0, thefirst motion information candidate list includes at least one of a firstspatial candidate indicating motion information of a first spatialneighboring block, a second spatial candidate indicating motioninformation of a second spatial neighboring block, and a temporalcandidate indicating motion information of a temporal neighboring blockin a co-located picture, a location of the first spatial neighboringblock is (UW, −1), a location of the second spatial neighboring block is(UW−1, −1), and a location of the temporal neighboring block is (DW−1,N−1).
 9. The video decoding method of claim 1, wherein based on thesplit boundary crossing an upper boundary and a lower boundary of thetarget block, an upper width of the second sub-partition being UW, alower width of the second sub-partition being DW, a size of the targetblock being N×N, and an x component of a top-left sample position of thetarget block being 0 and a y component of the top-left sample positionbeing 0, the second motion information candidate list includes at leastone of a third spatial candidate indicating motion information of athird spatial neighboring block, and a temporal candidate indicatingmotion information of a temporal neighboring block in a co-locatedpicture, a location of the third spatial neighboring block is (N−1−UW,−1), and a location of the temporal neighboring block is (N, N).
 10. Thevideo decoding method of claim 1, wherein based on the split boundarycrossing a left boundary and a right boundary of the target block, aleft height of the first sub-partition being LH, and an x component of atop-left sample position of the target block being 0 and a y componentof the top-left sample position being 0, the first motion informationcandidate list includes at least one of a first spatial candidateindicating motion information of a first spatial neighboring block, asecond spatial candidate indicating motion information of a secondspatial neighboring block, and a temporal candidate indicating motioninformation of a temporal neighboring block in a co-located picture, alocation of the first spatial neighboring block is (−1, LH), a locationof the second spatial neighboring block is (−1, LH−1), and a location ofthe temporal neighboring block may be (0, LH−1).
 11. A video encodingmethod performed by an encoding apparatus, comprising: splitting atarget block into a first sub-partition and a second sub-partition;deriving a first motion information candidate list for the firstsub-partition and a second motion information candidate list for thesecond sub-partition; deriving prediction samples in the firstsub-partition based on the first motion information candidate list;deriving prediction samples in the second sub-partition based on thesecond motion information candidate list; deriving residual samples ofthe target block based on the prediction samples in the firstsub-partition and the prediction samples in the second sub-partition;and encoding a bitstream including residual information and splitinformation for the target block, wherein the first sub-partition andthe second sub-partition are non-rectangular partitions, and wherein thesplit information includes information on an angle of a split boundaryand a distance between the split boundary and a center of the targetblock, wherein the target block is split into the first sub-partitionand the second sub-partition through the split boundary derived based onthe information on the angle of the split boundary and the distancebetween the split boundary and the center of the target block, andwherein based on a right height of the second sub-partition being RH, asize of the target block being N×N, and an x component of a top-leftsample position of the target block being 0 and a y component of thetop-left sample position being 0, the second motion informationcandidate list includes at least one of a first spatial candidateindicating motion information of a first spatial neighboring block and asecond spatial candidate indicating motion information of a secondspatial neighboring block, a location of the first spatial neighboringblock is (N, N−1−RH), and a location of the second spatial neighboringblock is (N−1, N−1−RH).
 12. A non-transitory computer-readable storagemedium storing a bitstream generated by a method, the method comprising:splitting a target block into a first sub-partition and a secondsub-partition; deriving a first motion information candidate list forthe first sub-partition and a second motion information candidate listfor the second sub-partition; deriving prediction samples in the firstsub-partition based on the first motion information candidate list;deriving prediction samples in the second sub-partition based on thesecond motion information candidate list; deriving residual samples ofthe target block based on the prediction samples in the firstsub-partition and the prediction samples in the second sub-partition;and generating the bitstream including residual information and splitinformation for the target block, wherein the first sub-partition andthe second sub-partition are non-rectangular partitions, and wherein thesplit information includes information on an angle of a split boundaryand a distance between the split boundary and a center of the targetblock, wherein the target block is split into the first sub-partitionand the second sub-partition through the split boundary derived based onthe information on the angle of the split boundary and the distancebetween the split boundary and the center of the target block, andwherein based on a right height of the second sub-partition being RH, asize of the target block being N×N, and an x component of a top-leftsample position of the target block being 0 and a y component of thetop-left sample position being 0, the second motion informationcandidate list includes at least one of a first spatial candidateindicating motion information of a first spatial neighboring block and asecond spatial candidate indicating motion information of a secondspatial neighboring block, a location of the first spatial neighboringblock is (N, N−1−RH), and a location of the second spatial neighboringblock is (N−1, N−1−RH).